W RLD June 2010 Volume 41 No. 2 aquaculture WORLD AQUACULTURE • Cocoa Bean meal • spotted rose snapper • Paddlefish polyculture • giant murrel • nile tilapia • JUNE 2010 Fish residue to grapes
World Aquaculture 1 WORLD AQUACULTURE Magazine World Aquaculture magazine is published by the World Aquaculture Society. The home office address is: World Aquaculture Society, 143 J.M. Parker Coliseum, Louisiana State University, Baton Rouge, Louisiana 70803, USA. Tel: +1-225-578-3137; Fax: +1-225-578-3493; e-mail: carolm@was.org. World Aquaculture Society Home Page: http://www.was.org WORLD AQUACULTURE SOCIETY OFFICERS, 2008-2009 President, Dr. Jay Parsons President-elect, Dr. Ricardo Martino Past President, Dr. Jeffrey Hinshaw Secretary, Dr. Rebecca Lochmann Treasurer, Dr. William Daniels DIRECTORS Dr. Graham Mair Dr. Junda Lin Dr. Michael Schwarz Dr. Jeong Yeol Lee Dr. David Little Dr. Yoram Avnimelech CHAPTER REPRESENTATIVES Roy Palmer (Asian Pacific) Douglas Drennan (USAS) Dr. Juan Pablo Lazo (Latin America and Caribbean) Dr. Sngchui Charles Bai (Korea) Hiroshi Fushimi (Japan) HOME OFFICE STAFF Carol Mendoza, Director, carolm@was.org Judy E. Andrasko, Assistant Director, JudyA@was.org WORLD AQUACULTURE EDITORIAL STAFF Robert R. Stickney, Editor-in-Chief Mary Nickum, Editor Amy Broussard, Layout Editor WAS CONFERENCES AND SALES John Cooksey, Director of Conferences and Sales World Aquaculture Conference Management P.O. Box 2302 Valley Center, CA 92082 Tel: +1-760-751-5005; Fax: +1-760-751-5003 e-mail: worldaqua@aol.com Manuscripts and Correspondence: Submit two (2) copies of all manuscripts and one (1) copy of correspondence to Mary Nickum, Editor, World Aquaculture Magazine, 16201 E. Keymar Drive, Fountain Hills, AZ 85268 USA. E-mail: mjnickum@ gmail.com. Letters to the Editor or other comments should be addressed to Editor-in-Chief Robert R. Stickney, 2700 Earl Rudder Freeway South, Suite 1800, College Station, TX 77845 USA. World Aquaculture (ISSN Number 1041-5602) is published quarterly by the World Aquaculture Society, 143 J.M. Parker Coliseum, Louisiana State University, Baton Rouge, Louisiana 70803 USA. Library subscriptions are $50 annually for United States addresses, and $65 annually for addresses outside the United States. Individual subscriptions are a benefit of membership in the World Aquaculture Society. Annual membership dues: Students, $40; Individuals, $60; Corporations (for-profit), $250; Sustaining, $100 (individuals or non-profits); Lifetime (individuals), $1,000; E-Membership, $10 (no publications, meeting discounts and not an active member in last five years). Periodicals Postage paid at Baton Rouge, Louisiana and additional mailing offices. Twenty-five percent of dues is designated for a subscription to World Aquaculture magazine. Postmaster: Send address changes to the World Aquaculture Society, 143 J.M. Parker Coliseum, Louisiana State University, Baton Rouge, Louisiana 70803 USA. ©2010, The World Aquaculture Society. ■ W RLD AQUACULTURE Vol. 41 No. 2 June 2010 Cover photo: Water fertilized by fish waste and residual feed can be used to grow horticultural produce, such as grapes. See page 53. (Continued on page 2) 6 World Food Crisis, FAO Alert and India M.N. Kutty 8 Growth performance of sex-reversed Nile tilapia (Oreochromis niloticus, Linnaeus) cage cultured in a waste-fed freshwater wetland Adity Sarbajna, Sandipan Gupta, Suman Bhusan Chakraborty, and Samir Banerjee 12 Use of discarded cocoa bean meal as a source of dietary energy for the production of African catfish (Clarias gariepinus, Burchell 1822) L.C Nwanna and O. F. Fashae 17 Farm-level efficiency and resource use: Application of stochastic frontier analysis to aquaculture farms in Southwest Nigeria Kolawole Ogundari 20 Spotted rose snapper (Lutjanus guttatus) aquaculture research and development as socio-economic alternative for Costa Rican fishing communities A. Herrera-Ulloa, J. Chacón-Guzmán, G. Zúñiga-Calero, R. Jiménez-Montealegre 30 Paddlefish Polyodon spathula polyculture with freshwater shrimp Macrobrachium rosenbergii William A. Wurts, Steven D. Mims and Richard J. Onders 33 The Oregon Hatchery Research Center: An experimental laboratory in a natural setting David L. G. Noakes and Charlie Corrarino 39 Markets for Honduran tilapia Suyapa Triminio Meyer and Daniel E. Meyer 42 Giant murrel farming, an urgent need for Indian fish farmers M.A. Haniffa, M. James Milton, Y. Ananth Kumar, S.V. Arun Singh and R. Arthi Manju 47 The role of the aquaculture demonstration project in the United States Maxwell H. Mayeaux
2 June 2010 From the Editor’s Desk In the March issue of World Aquaculture I asked members to respond to a survey about your position on moving to online publication. The response has been – how should I put it? – abysmal. The problem was, I hope, associated with following the instructions on getting to the survey on the website that was provided. As a result, the survey will remain up until August 1, 2010. The Publications Committee will be discussing various issues surrounding WAS publications and will certainly be interested in the results of the survey, but unless we get a good response to the survey, there will be very little guidance provided. So, here are the step-by-step instructions on how to get to the survey: 1. Log on to http://texas-sea-grant.tamu.edu/About/ Stickney.html 2. In the third paragraph on the page, click on the highlighted link “World Aquaculture, the magazine of the World Aquaculture Society.” 3. That will open the survey. Here are the questions in the survey should you like to email, fax, or send a response to the survey through the mail. 1. Do you support the idea of changing to online publication of World Aquaculture? Yes No 2. If given the option, which would you prefer to receive? Online Print 3. How many issues of World Aquaculture would you like to see each year? Four Six Other If you selected “Other,” please provide the number of issues you would like to see annually. 4. Should at least one author of each article published in World Aquaculture be a member of the World Aquaculture Society? Yes No, anyone with pertinent information should be encouraged to submit No, but non-members would receive a PDF of their article, not a copy of the entire issue in which their article appears. 5. Are there particular aquaculture topics that you would like to seem more articles about in World Aquaculture? Send your responses as follows: Email: stickney@tamu.edu Fax: +1-979-845-7525 Regular mail: Robert R. Stickney P.O. Box 1081 Hearne, Texas 77859-1081 USA Thank you in advance for your participation. — Robert R. Stickney Editor-in-Chief 53 Fish culture in horticulture-based polythenelined farm ponds: Status and potential Sudhakar T. Indulkar and Satyajit S. Belsare 58 Growth and survival of Macrobrachium americanum Bate, 1868 juvenile prawns (Crustacea, Decapoda, Palaemonidae) stocked in tanks at different sizes Marcelo U. García-Guerrero and Javier Orduña Rojas 61 Fisheries and sustainable livelihoods of fishing communities in Nigeria Ahmed Gomna Kuta Departments 4 On a personal note … 4 Loss of a shrimp culture pioneer 5 USAS Chapter status report 23 Imre Csavas 24 Special book promotion through October 31, 2010 26 A look back at San Diego 57 Asian-Pacific Chapter Report 70 Advertisers’ Index 71 Calendar 72 Membership Application (Continued from page 1) Contents
World Aquaculture 3 President’s column As with any new President, it is with a great degree of honor and pride that I take the helm of the World Aquaculture Society. The society has just completed another successful Triennial meeting with our partners from the National Shellfisheries Association and the Fish Culture Section of the American Fisheries Society. The meeting was financially successful, as well as scientifically rewarding, with one of the largest programs ever presented during the Triennial events. There was a total of 2,549 participants (1,687 conference delegates and 862 trade show attendees). As well, there were 172 trade show booths, 91 sessions and 1,217 abstracts. I want to acknowledge the excellent job and offer my thanks to John Cooksey and team and the members of the Triennial program and steering committees. The society continues to be a very stable organization in terms of our finances, membership, services and products that we offer (web site, journal, magazine, books, conferences, etc.). However, while WAS is on a solid footing, that does not mean we should rest on our laurels. There continue to be exciting challenges in terms of the research needs to support the ongoing development of the aquaculture sector worldwide in ensuring that it grows in a responsible manner. And, the WAS has an important role to play in providing forums and vehicles for the discussion and communication of leading edge research and technology. The WAS Board of Directors has also been active in ensuring that the society continues to grow and be a globally representative organization. We will continue our efforts this year to promote and expand WAS membership in all parts of the world and to offer opportunities to hold regional conferences in areas where we previously have not met. One additional initiative that was officially launched in the last issue of the World Aquaculture Magazine is the establishment of the “Fellows of the World Aquaculture Society Program.” Fellows of the World Aquaculture Society will be individuals “who have made outstanding achievements in aquaculture science, industry, outreach or extension as recognized by their peers.” A Fellow of the World Aquaculture Society program will bring a greater level of recognition to Fellows and respectability to the World Aquaculture Society. Fellows of the World Aquaculture Society will also serve as distinguished colleagues to whom the World Aquaculture Society and its members can look for guidance as global aquaculture evolves. The World Aquaculture Society presently offers Honorary Life Membership to distinguished persons, and the Board of Directors wish to keep the current Honorary Life Membership intact as the highest recognition of the Society. The new Fellows award seeks to distinguish itself from our other awards by creating a category of recognition to the many aquaculture professionals spread throughout the world who have contributed to developing aquaculture as members of the World Aquaculture Society. We have recently sent an e-mail to all members encouraging you to submit a nomination and I do so again. Further information on this program can be found on our WAS web site at www.was.org. During my term of office, I am also committed to building our membership, further engaging students in our organization and completing and implementing our new strategic plan. I will elaborate on these topics in future editions of this column. And during my term as president, I welcome comments and feedback for any initiative or idea that you might have that will collectively allow us to continue to grow the society. Please contact me at Jay.Parsons@dfo-mpo.gc.ca. — Jay Parsons, PhD. President
4 June 2010 On a personal note ... It is with great sadness that I report on the passing of Homer Buck on April 30, 2010. I first met Homer during either the late 1960s or early 1970s, while I was still in graduate school. The occasion, as I recall was an American Fisheries Society meeting. Homer was a fisheries biologist with the Illinois Natural History Survey and was highly respected in the profession. He was the type of person who immediately became your best friend when you met him. Homer contacted me late last year to see if I’d be interested in publishing a paper on the potential of Asian carp to help feed the world. The paper, by Homer and a colleague, appeared in the December 2009 issue of World Aquaculture. Homer, who had suffered from a stroke some time ago, called me to express his pleasure with the article and I am very glad that he got to see it before his death. Another friend and colleague, Richard Noble, who was passing through Texas early in April, called to see if I’d be available for lunch. Rich had been on the faculty at Texas A&M with me during my first stint at the university from 1975-1984. A year or so after I left Texas A&M, Rich took a position at North Carolina State University, from which he retired a few years ago. I mentioned that we’d published Homer’s article. Rich said, “I just saw him recently.” I knew that Homer had retired in North Carolina, and of course knew that Rich was one of the multitude who were friends of Homer. In any case, Rich had visited Homer and his wife Ruth several times. We had a nice lunch, reminiscing about Homer for much of it. I had hoped to have the opportunity to get to North Carolina and see Homer, but of course that will never happen. It had been many years since I’d last seen this kind and gentle man, but I am grateful that we at least had some communication recently. Homer was a source of an incredible amount of information that he shared and disseminated through presentations, publications and personal interactions. His was a long and productive career and I kept running into his work as I was conducting my own research. His contributions to both aquaculture and fisheries were significant. Homer Buck will be remembered and sorely missed by those of us who were fortunate to have crossed his path. — Robert R. Stickney Editor-in-Chief Loss of a shrimp culture pioneer Jim Norris, one of the true pioneers of shrimp aquaculture died from pancreatic cancer on May 1, 2010 at the VNA Hospice House in Vero Beach, Florida USA. The 64-year-old native South Carolinian and graduate of the University of Miami designed and operated some of the earliest and most advanced shrimp hatcheries in the Americas. His 35-year work with shrimp hatcheries and genetic improvement programs involved long-term assignments in Honduras, Ecuador and Florida. Creative, and always with a sense of humor, Jim worked his way through the art and science of shrimp larviculture, developing successful operations and life-long friendships. In 1974, Jim interviewed for the post of hatchery manager for the project that Sea Farms, Inc. was developing in Honduras. At the time Jim had been working at the University of Miami shrimp hatchery research project at the Turkey Point Nuclear Plant. Jim’s appearance in those days was not what one would call conservative –long hair and beard – but it was clear that he was a serious marine biologist keenly interested in how best to spawn and rear shrimp and ready to devote himself to making it happen. He was an easy choice for the job. Jim headed to Honduras where over the next several years he put together the finest and largest hatchery facility and team of its time in the Western Hemisphere, if not the world. Jim started by using wild brood shrimp fished off Nicaragua, but gradually developed maturation and breeding programs and a first-class hatchery team that eventually supported over 200 ha of farm ponds. His other activities included shell collecting, fly fishing, dove hunting and Rotary Club meetings on Friday nights in Choluteca. In 1981, Jim returned Miami to head up the hatchery phase of Sea Farms’ international expansion plans. This included refurbishing the original hatchery facility at Summerland Key to house the company’s breeding and maturation program. In 1983, he moved to Ecuador to build the hatchery for Sea Farms’ El Rosario project. Three years later he returned to the Miami office to supervise hatchery operations and investigate other locations for company expansion, particularly in Brazil. Jim returned to Summerland Key in 1988 to refurbish and reopen the hatchery to provide postlarvae (PL) for the Sea Farms Granjas Marinas San Bernardo joint venture in Honduras He also reinstituted the breeding and maturation program that had been temporarily shut down. The hatchery started operating in 1990 and quickly went from its design capac- (Continued on page 71)
World Aquaculture 5 USAS Chapter status report It is my great pleasure to present this update on behalf of the United States Aquaculture Society (USAS), a chapter of the World Aquaculture Society (WAS). As I write this update, I am three months into my year-long term as USAS chapter president, which officially began at the USAS annual meeting in late February. As many of you realize, this year’s USAS annual meeting was held in conjunction with the WAS triennial meeting Aquaculture 2010 in San Diego. Triennial meetings are always special because they are the combined annual meetings of WAS, the National Shellfisheries Association and the Fish Culture Section of the American Fisheries Society and, as such, are the largest aquaculture conferences and tradeshows held worldwide. However, this year’s triennial held special meaning for the USAS chapter because it marked not only our annual meeting but the 20th Anniversary of the creation of the USAS chapter. This auspicious milestone for our Chapter was acknowledged by presenting USAS Chapter members with membership pins denoting their years of continuous membership and Certificates of Appreciation for their years of dedication and service to furthering the interests of Aquaculture in the United States. A milestone such as this; however, cannot be simply acknowledged without reflection on the past and contemplation of future of the Chapter. When the United States Aquaculture Society was created twenty years ago, it was done so not to separate the chapter from the parent society WAS, but rather to allow both groups to better meet the diverse needs of their members. The primary venues through which USAS seeks to meet the needs of our members are through our US annual meetings and tradeshows that address relevant and timely issues identified by our membership, student awards that support development of the next generation of aquaculture professionals and publications to fill information gaps. Using this model, the USAS chapter membership has now grown to over 1,000 members (132 of which are students) and over $168,000 in total assets. Thus, even as we move forward in challenging economic times, the USAS chapter is financially stable and continues to seek ways to turn our economic assets into value for our membership including additional venues for annual meetings, new student and young professional awards, more publications and an increased commitment to outreach, education and professional networking through traditional and modern communication venues. The recently approved updated USAS Chapter 5-year Strategic Plan reflects these goals and provides both a roadmap and benchmarks to assess our progress. As a Chapter, one of our continuing endeavors is to hold annual meetings that showcase US aquaculture and promote information exchange to the benefit of our membership. As you read this it’s not to early to make plans to attend Aquaculture America 2011, February 28-March 3 in beautiful New Orleans, Louisianna. The Program Committee consisting of Steering Committee Chair, Reginald Blaylock; Technical Program Chair, Chris Green; NAA representative, Betsy Hart; and Conference manager, John Cooksey; are organizing a meeting that will no doubt accomplish our goals and be fabulous to boot. The abstract deadline of August 1, 2010 is fast approaching. This deadline is especially pertinent to our student members because in order to be eligible for the more than $6,000 awarded annually to our student members at the USAS meetings, abstracts must be submitted and student membership current by the abstract deadline for consideration for any award. These awards include Andrew McElwain was awarded the second place student presentation award during the March 2010 meeting of the World Aquaculture Society in San Diego, CA. McElwain received a BS in biology from Westfield State (Massachusetts) College in 2002. He continued to pursue biology at Middle Tennessee State University (Murfreesboro, TN) where he studied parasitic copepods with Dr. George Benz. After earning his MS in Fall 2007, McElwain taught General Biology and Microbiology at Columbia State Community College (Franklin, TN) and Motlow State Community College (Smyrna, TN) until Spring 2009. McElwain is now a PhD student with Dr. Ash Bullard in the Department of Fisheries and Allied Aquacultures at Auburn University and wants to study diseases of aquatic animals. Dr. Ash Bullard (left) and Andrew McElwain McElwain earns second place (Continued on page 68)
6 June 2010 Editor’s notebook The note from Dr. Kutty (at right) was received by the editorial staff of World Aquaculture in March of this year. As you will see, it relates to a paper by Jon Gulbrandsen published in the December 2009 issue (pp 1011,70). Aside from some adjustments in formatting to fit our style, the note and the article, “World Food Crisis, FAO Alert and India,” which is published below, have not been modified. World Food Crisis, FAO Alert and India M.N. Kutty The world food crisis is getting closer than expected as alerted in FAO Director General Jacques Diouf’s recent (2008) announcement. Some well considered steps taken soon might avert a major collapse in India, from the immediate context, as indicated by the Central Minister for Food. However, our long-term perspective of provision of adequate food for the teeming masses, in spite of some population control measures (implemented more effectively in China), has to change drastically. The landbased food production systems, despite further expansion and intensification, are limiting. We have to turn to water and not too much to land for additional food production, through available sustainable technologies and evolving new innovations, which would ensure our food and nutritional security. After all, as understood water is the medium of transfer of energy and nutrients in food production systems whether in land or water – obviously the reason for the beginning of life in water, the trick of energy synthesis and trapping using sunlight and nutrients, one in which we heavily depend on. A cubic metre of water can be much more productive, useful and easier to deal with in this context, if judiciously managed. Let us prepare to spread from land to water – modifying our present food production systems and taking to new foods, on priority, if not in our immediate and short term development efforts, in the long term perspective and cultivate water more and cultivate sustainability; the recourse is through aquaculture for food to save the planet and man, delaying a little perhaps, our race to conquer the outer space. So the time we spend in its (aqua) development would spell more than what it ever did. Besides hydroponics, both edible plants and aquatic animals/fish etc can be farmed immediately by expanding available aquaculture technologies in the inland and near-shore waters (in which also China excels by producing about 70 percent of global production, probably achieved through China’s greater needs as well as vision, while India is a poor second, accounting for only <6 percent. China produces about 11 million tons of aquatic Comments on Dr. Jon Gulbrandsen’s “Solving the food crisis – on an ocean planet,” World Aquaculture, December 2009 The following note, “World Food Crisis, FAO Alert and India” was written by me specifically to alert some in India in 2008. I feel this is still relevant from the context of Dr. Jon Gulbrandsen’s “Solving the food crisis – on an ocean planet”, which appeared in World Aquaculture Vol. 40 No. 4 December 2009. I agree with Dr. Gilbrandson’s stress on the need for turning to the oceans for solving global food crisis, but would prefer to concentrate more on primary production systems as the main source for food. In any case, on a long term basis, it might help if we tap more the more basal and efficient trophic systems for food production, choosing first those close to human needs and preferences, but it seems that from the present world context the turn of research intensification will be decided more by the preferences of the donors and investors rather than that of the food needs of the less privileged, which are more seriously under threat now. Current address: Narayan Kutty 802 Betlin Ave Cupertino, CA 95014, USA
World Aquaculture 7 Table 1. Aqua food production by capture and aquaculture in 2004 in World, India and China (in lakh metric tons) (Based on FAO 2006) Fishes Aquatic Plants Total WORLD Capture 950.01 14.32 964.38 (61.9%) Aquaculture 454.68 139.27 593.95 (38.1%) Total 1404.74 153.69 1558.33 (100%) INDIA Capture 36.2 Nil 36.2 (59.4%) Culture 24.7 Nil 24.7 (40.6%) Total 60.9 Nil 60.9 (100%) CHINA Capture 168.9 3.8 172.7 (29.5%) Culture 306.1 107.1 413.2 (70.5%) Total 475.0 110.9 585.9 (100%) weeds mainly for food, while India is yet to make an entry!). Even expanding this production to the optimum sustainable level, we would fall short in a short time in history. There is a great need for expanding food production from tended waters farther onto the sea - we can utilize much of the area in India’s EEZ of 2 million km2, most of which is untouched for aquaculture. As a futuristic development for survival, in the context of the present century and after, the proposed exploitation of our vast open sea waters would be a necessity. From a short time perspective India might be in a position to meet the food deficits through judicious interventions, as indicated, and allowable intensification of traditional food production systems. But on a long term perspective, it would be necessary to turn to newer pastures spread across the ocean fringes and beyond in waters, which are larger than any land mass available, for ensuring survival of our teeming millions. M. N. Kutty Former FAO/UN Expert “Prasadam” Puthur, Palakkad 678001, Kerala Email: kuttymn@gmail.com 10 April 2008 Dr. Gulbrandsen responds Dear Narayanan, I have read your article “World Food Crisis, FAO Alert and India” and couldn’t agree more. Just as yourself, I mention the possibility of utilizing lower trophic levels in my article, which no doubt is a very important point, but I turn to international management as the main culprit because, in principle, the solutions are already known – we are just not able to make the full use of them. I think the main problem is that protagonists in question (politicians, investors and scientists) do not communicate, but rather live in different worlds as it were, so what I try to do, is to define an area in which these three worlds can interact more efficiently. I give just a few examples on how this may be done, but it is important to realize that what I present is a work model, and not a detailed strategy, but at the very least, it is a point at which to start. What I seek through my article, is the cooperation of politicians, economists and scientists to develop the idea further, and to push the agenda with me, be it towards the UN or other international bodies. I have, among others, received the support of two national governments, including my own, but they have so far stumbled in protocol, which is the first step in an endless loop of arguments of why we can’t do anything, even if we want to. Thank you so much for your support! — Jon
8 June 2010 Growth performance of sex-reversed Nile tilapia (Oreochromis niloticus, Linnaeus) cage cultured in a waste-fed freshwater wetland Adity Sarbajna, 1 Sandipan Gupta, 2 Suman Bhusan Chakraborty, 3 and Samir Banerjee4 Currently, tilapia culture is widely practiced in many tropical and subtropical regions of the world as the cheap source of animal protein (Guerrero 1982, Alvendia-Casauay and Carino 1988) and it is the second largest group of farmed finfish species, only after carp (Popma and Masser 1999). Tilapia has been described as the most important aquaculture species of 21st century (Shelton 2002). Several studies have been conducted to increase tilapia production and it has been observed that androgen treated, all-male tilapia populations grow faster than untreated, mixed-sex tilapia populations (Guerrero and Guerrero 1975, Hanson et.al.1983, Muhaya 1985, Jae-Yoon Jo et.al.1988, Pandian and Varadaraj 1988). Tilapia have been considered as a suitable species for cage culture by many workers (Coche 1982, Rackoy and McGinty 1989, Santiago and Arcilla 1993, Masser 1997, Dikel et. al. 2005) and can be grown to market size in cages without hampering the culture of other fish species in the same pond. In India, the utilization of wastewater for aquaculture purposes has been practiced from a long time (Ghosh 1990, Krishnamoorthi 1990, Jana 1998, Bansal et.al. 2007). The organic load of the discharged wastes provides an excellent source of nutrients for the growing fish and thus reduces the extra costs associated with providing supplemental food (Raychaudhuri et.al.2008). Inasmuch as tilapia are adaptable to poor water quality conditions (Popma and Masser 1999), they are suitable for culture in waste fed freshwater ecosystems. No work has previously been done in India to determine the growth performance of tilapia in cages in waste-fed freshwater wetlands. Therefore, the main aim of our study was to examine the growth potential of sex reversed tilapia in cage culture in a waste fed freshwater ecosystem. Study Methods Collection and Acclimatization of the fish Juveniles of a pure strain of Oreochromis niloticus (Linnaeus) were collected from a fish hatchery, Naihati, West Bengal and were acclimatized to laboratory conditions. They were kept in 5 L glass tanks under similar photoperiod (14 L:10 D), temperature (27 ± 2ºC) and density (10 fish/L). Preparation of Hormone Treated Food A fry feed, crude protein content 30 percent and total digestible energy 3000 ± 400 kcal/kg, was prepared from a mixture of fine fish meal, rice bran and other ingredients and sieved to a size of less than 1 mm. Hormone treated diet was prepared by the alcohol evaporation technique (Shelton et. al. 1978). The synthetic androgen, 17α-methyl testosterone (17α MT; “Sigma” St. Louis, Missouri USA) was dissolved in 95 percent ethanol and then mixed with the pellets (1 L ethanol/kg pellets). The 17α MT containing wet pellets were dried in the open air. Control pellets were prepared similarly without the addition of 17α MT. Fresh food was prepared weekly and stored in a cool place. Hormonal Treatment One group of juveniles was fed the hormone treated diet daily at 10 mg/kg for 30 days (Chakraborty et.al. 2007) and the other group was fed the control diet at the same rate for the same duration. After one month, about 98 percent males was obtained from the hormone treated group and a ratio of Photograph of hormone treated (A) and control (B) tilapia at the time of final harvest.
World Aquaculture 9 50:50 percent males:females was obtained from the control group (Chakraborty et.al. 2007). Selection of the Site A sewage-fed pond at Jhagrashisa in East Kolkata Wetland (coordinates 22˚25’-22˚40’N latitude and 88˚20’- 88˚35’E longitude) was selected for the experiment. Transportation and Release of Fry in Cages The treated and control fry were transported to the field using oxygen packs. The oxygen packs containing the tilapia fry were at first floated in the pond water for about 30 minutes for temperature acclimatization after which the fry were released into the cages. The size of the cages was 1m x 1m x 1m. Fry were released in the cages in the early morning. Treated (0.76±0.016g) and control (0.38±0.028g) fry were stocked in separate cages at a density of 25 fry/cage in three replicates. Collection of Data Body weight (BW) of fish from both the groups was measured every four weeks from December 2005 to May 2006. Four water quality parameters, dissolved oxygen, free CO2, temperature and pH were measured following standard methods (APHA 1998) at the time of fish sampling. The mean weight gain per month for both the groups was also calculated at the end of the culture period. Statistical Analysis The results are presented as mean ± standard deviation. Fish growth rates were subjected to one-way analysis of variance (ANOVA) to test the effect of hormone treatment on growth parameters. Results and Discussion A linear increase in the mean body weight of the fish with respect to time throughout the culture period was observed for both the treated and control groups (Figure 1). This indicates that the environmental conditions for fish growth were favorable in the culture pond as previously mentioned by Mohammad (2006). After one month of rearing in the laboratory, the hormone treated groups attained better weight (0.76±0.016g) compared to the control groups (0.38±0.028g). Moreover, at the end of the culture period, the hormone treated monosex tilapia population obtained a significantly higher mean body weight than the control mixed-sex population (Figure 1). In addition, hormone treated fish showed significantly higher weight gains throughout the culture period (Figure 2). This result is in agreement with other similar studies (Guerrero and Guerreo 1975, Shelton et.al. 1978, Hanson et.al.1983, Muhaya 1985, Jae-Yoon Jo et.al.1988, Pandian and Varadaraj 1988). The increased growth performance of the androgen-treated sex reversed tilapia may be attributed to the phenomenon of muscular hypertrophy by increased muscle protein synthesis through testosterone treatment (Bhasin et. al. 2001). The total production obtained in five months of culture was 3.70 kg/m3 for the treated group and 2.41 kg/m3 in the controls. The production obtained was significantly higher in the treated group than in the control group. Thus, cage culture of hormone treated, monosex tilapia in a waste fed wetland Fig. 1. Comparative body weight (g) of control and hormone treated tilapia population during cage culture. Fig. 2. Comparative account of mean monthly weight gain (g) for control and hormone treated tilapia population during cage culture. was more beneficial than culture of mixed-sex tilapia reared under using the same culture method and conditions. From Figure 2 it is clear that for the androgen-treated group of fish, the mean monthly weight gain gradually increased with culture duration and was highest during the fourth month. Comparatively lower mean weight gain was obtained during the fifth month than the fourth month. This may be a result of a decrease in the residual effect of testosterone on somatic growth of the fish. On the other hand, for the control group, the monthly mean weight gain was highest in the third month of the culture period. Culture of that group during an additional two months again showed comparatively lower mean weight gain than that in the third month. Tilapia are reported to sexually mature at about three months (Chapman 1992). Hence, the reduction in weight gain after three months in the control tilapia population may have been a result of the utilization of most of the food energy for reproductive purposes. So it can be concluded that cage culture of hormone treated monosex tilapia for four months and mixed-sex control tilapia for three months in a waste fed ecosystem is optimum to get high production with a minimum culture period.
10 June 2010 Notes 1Department of Zoology, Surendranath College, Kolkata, West Bengal, India 2Aquaculture Research Unit, Department of Zoology, University of Calcutta, Kolkata, West Bengal, India 3Department of Zoology, Serampore College, Serampore, West Bengal, India 4Aquaculture Research Unit, Department of Zoology, University of Calcutta, 35,Ballygunge Circular Road, Kolkata –700019, West Bengal, India. E-mail Address: samirbancu@gmail.com Acknowledgment Authors thank Mr. Alok Mondal, the owner of “Jhagrashisa Bheri” for his cooperation to continue our culture experiments and also to all the working staff of this bheri for their kind help. We also thank Mr. Debashis Majumder, Bidhan Chandra Krishi Viswavidyalaya for his valuable guidance for statistical analysis. References Alvendia-Casauay, A. and V.S. Carino. 1988. Gonadal sex differentiation in Oreochromis niloticus. Pages 121-124 In R.S.V. Pullin, T. Bhukaswan, K.Tonguthai and J.L.MacLean, editors. The Second International Symposium on Tilapia in Aquaculture. ICLARM Conference Proceedings. Department of Fisheries, Bangkok, Thailand, and International Center for Living Aquatic Resources Management, Manila, Philippines. APHA (American Public Health Association, American Water Works Association, and Water Pollution Control federation). 1998. Standard methods for the examination of water and wastewater, 20th edition, American Public Health Association. Washington, District of Columbia, U.S.A. Bansal, A.K., A. Mitra, R.P. Arora, T. Gupta and B.S.M. Singhvi. 2007. Biological treatment of domestic wastewater for aquaculture. Journal of Agricultural and Biological Science 2:6-12 Bhasin S., L. Woodhouse and T. W. Storer. 2001. Proof of the effect of testosterone on skeletal muscle. Journal of Endocrinology 170:27-38. Chakraborty, S.B., A. Sarbajna, D. Majumder and S. Banerjee. 2007. Effects of differential dose and duration of 17 α- methyl testosterone treatment on sex reversal of Nile tilapia, Oreochromis niloticus at different age groups under Indian perspectives. Asian Journal of Microbiology, Biotechnology and Environmental Science 9:705-710. Chapman, F.A. 1992. Culture of hybrid tilapia: A reference profile. Circular 1051, Department of Fisheries and Aquatic Sciences, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainsville, Florida, USA. Coche, A.G. 1982. Cage culture of tilapias. Pages 205-246 In R.S.V. Pullin and R.H. Lowe-McConnell, editors. The Biology and Culture of Tilapias. ICLARM Conference Proceedings, vol.7. International Center for Living Aquatic Resources Management, Manila, Philippines. Dikel, S., G.A. Kiriş and M.V. Alev. 2005. The Potential of Phytoplankton-based culture of tilapia (Oreochromis niloticus) in floating cages in Seyhan Dam Lake. In the 7th Balkan Conference on Operational Research. “BACOR 05”, Constanta, Romania. Ghosh, D. 1990. Wastewater-fed aquaculture in the wetlands of Calcutta. Pages 251-266 In P. Edwards and R. Pullin, editors. Wastewater-fed aquaculture. Asian Institute of Technology, Bangkok, Thailand. Guerrero, R.D. and L.A. Guerrero, 1975: Monosex culture of male and female T. mossambica in ponds at three stocking rates. Philippines Journal of Biology 4:129-134 Guerreo, R.D.1982. Control of tilapia reproduction. Pages 309316 In R.S.V. Pullin and R.H. Lowe-McConnell, editors. The biology and culture of tilapias. ICLARM Conference Proceedings. International Center for Living Aquatic Resource Management, Manila, Philippines. Hanson, T.R., R.O. Smitherman, W.L. Shelton and R.A. Dunham.1983. Growth comparison of monosex tilapia produced by separation of sexes, hybridization and sex reversal. Pages 570579 In L. Fishelson and Z. Yaron, compilers. Proceedings of the International Symposium on Tilapia in Aquaculture 8-13 May 1983. Tel Aviv University, Israel. Jana, B.B. 1998. Sewage-fed aquaculture: The Calcutta model. Ecological Engineering 11:73-85. Jo, J-Y, R.O. Smitherman and L.L. Behrends. 1988. Effects of dietary 17 α- methyl testosterone on sex reversal and growth of Oreochromis aureus. Pages 203-207 In R.S.V. Pullin, T. Bhukaswan, K. Tonguthai and J.L. MacLean, editors. The Second International Symposium on Tilapia in Aquaculture. ICLARM Conference Proceedings. Department of Fisheries, Bangkok, Thailand, and International Center for Living Aquatic Resources Management, Manila, Philippines. Krishnamoorthi, K.P. 1990. Present status of sewage-fed fish culture in India. Pages 99-103 In P. Edwards and R. Pullin, editors. Wastewater-fed aquaculture. Asian Institute of Technology, Bangkok, Thailand. Masser, M. P. 1997. Cage culture species suitable for cage culture. Southern Regional Aquaculture Center. Publication no.163. Mohammad, T.R. 2006. Comparative study of growth performance of three strains of Nile tilapia, Oreochromis niloticus, L. at two stocking densities. Aquaculture Research 37:172-179. Muhaya, B.B.M. 1985. Growth comparison of Tilapia nilotica males produced through oral administration of methyl testosterone at varying levels and duration. Master’s Thesis. Auburn University, Auburn, Alabama. USA Pandian, T.J. and K. Varadaraj. 1988. Techniques for producing all male and all triploid Oreochromis mossambicus. Pages 243249 In R.S.V. Pullin, T. Bhukaswan, K. Tonguthai and J.L. MacLean, editors. The Second International Symposium on Tilapia in Aquaculture. ICLARM conference Proceedings. Department of Fisheries. Bangkok, Thailand, and International Center for Living Aquatic Resources Management, Manila, Philippines. Popma, T. and M.P. Masser. 1999. Tilapia: life history and biology. Southern Regional Aquaculture Center Publication, Publication No. 283. Rackoy, J.E. and A.S. McGinty. 1989. Cage culture of tilapia. Southern Regional Aquaculture Center Publication, Publication No.281. Raychaudhuri, S., M. Mishra, S. Salodkar, M. Sudarshan and A.R. Thakur. 2008. Traditional aquaculture practice at East Calcutta wetland: The safety assessment. American Journal of Environmental Sciences 4:140-144. Santiago, A.E. and R.P. Arcilla. 1993. Tilapia cage culture and the dissolved oxygen trends in Sampaloc Lake, The Phillipines. Environmental Monitoring and Assessment 24:243-255. Shelton, W.L., K.D. Hopkins and G.L. Jensen. 1978. Use of hormones to produce monosex tilapia for aquaculture. Pages 10-33. In R.O. Smitherman, W.L. Shelton, J.H. Grover, editors. Culture of Exotic Fishes Symposium Proceedings. Fish Culture Section, American Fisheries Society, Auburn, Alabama. USA. Shelton, W.L. 2002. Tilapia culture in the 21st century. Pages 1-20. In R.D. Guerrero III and M.R. Guerrero-del Castillo, editors. Proceedings of the International Forum on Tilapia Farming in the 21st Century (Tilapia Forum 2002). Philippine Fisheries Association Inc. Los, Banos, Laguna, Philippines.
World Aquaculture 11
12 June 2010 Use of discarded cocoa bean meal as a source of dietary energy for the production of African catfish (Clarias gariepinus, Burchell 1822) L.C Nwanna1 and O. F. Fashae At least 10 percent of harvested cocoa bean seed (Theobroma cacao) is discarded as waste by-product by cocoa processing industries/communities in Nigeria. Nwanna et al. (2008) described discarded cocoa bean seed as the whole bean unfit for human consumption. The volume of this waste in relation to the total quantity of cocoa produced annually attracted the interests of some scientists who opined that the product could be used in animal feeds. Adegbola and Omole (1973) characterized the chemical and amino acid composition of the discarded cocoa bean seed meal. They reported that the bean has great potential as an alternative animal feed. The proximate composition reported was supported by our earlier investigation (Nwanna et al. 2008). However, as nutritionally rich as this alternative feed ingredient is, there is a dearth of information on its use as a dietary energy source in fish nutrition. Energy feedstuffs are low in protein and contain about 12 percent crude protein, of which 75-80 percent is digestible (Fagbenro et al. 2000). They are also useful as texturing and binding agents in pelleted feeds. Corn is usually used as a dietary energy source in fish feed. It contains 65-75 percent starch, 10 percent protein, 3.5-5 percent lipid, while the outer tissue of the grain contains vitamins (Purseglove 1985). Most fish feed formulations contain between 20-30 percent corn. As a dietary carbohydrate, corn has the ability to reduce the oxidation of dietary protein for energy (Viola and Arieli 1983, Hanley 1993, Nwanna et al. 2003) that invariably minimizes the quantity/costs of dietary protein. However, competition for its use in human foods and animal feeds limits the availability/quantity and, hence, increases the price. This has necessitated research to find cheaper alternative non-conventional energy sources that will not compromise growth and physiological functions. Inasmuch as the nutritional quality of discarded cocoa bean seed meal (protein 16 percent, fat 45.1 percent, carbohydrate 19 percent) compares favorably well with that of yellow corn (Nwanna et al. 2008), it may be hypothesized that discarded cocoa bean meal (DCM) can adequately replace corn in fish diets. The present study investigated the effect of replacement of yellow corn with discarded cocoa bean seed meal on the growth and nutrient utilization of African catfish (Clarias gariepinus). Economic implication of the replacement was estimated using the incidence of cost and profit index model of Vincke (1969) by assuming 50 percent of the cost of corn for the DCM. Study Materials and Methods Sample collection and preparation The discarded cocoa bean seed used for the study was collected on March 2008, from Stanmark Cocoa Processing Company, Ondo Road, Akure in Ondo State. Thereafter, the cocoa beans were sundried at a temperature of 27-30ºC to make the husk easier to remove. The husks were mechanically removed by hand and the inner cocoa pods were sundried again. The dried pods were blended into fine particles to form the DCM. Diet preparation Other feedstuffs including, fishmeal, soybean meal, ground nut cake, yellow corn, cod liver oil, vitaminmineral premix, methionine and carboxymethy cellulose (Table 1) were purchased from Adedom Feeds Vendor, Akure in Ondo State. The required quantities of each ingredient making up a 40 percent crude protein diet were mixed together and pelleted to provide the basal diet or control diet, diet 1. Then, in diets 2, 3, 4, and 5, DCM replaced 25, 50, 75 percent and 100 percent of the corn in the basal diet, respectively. The dried feed ingredients were mixed with the vitamin-mineral premix, starch and DLmethionine and a small amount of water and made into 1-mm diameter pellets. The pellets were sun dried to a constant moisture level (<10 percent), packed in airtight polyethylene bags and stored at -20ºC before use. Diet samples were analysed for their proximate composition (Table 2) using the methods of AOAC (1990). Gross energy of the diets was calculated using KJ/g) values of 23.0, 38.1 and 17.2 for protein, lipid and carbohydrate, respectively (Tacon 1990).
World Aquaculture 13 Table 1. Ingredient composition of experimental diets (g/100 g). Ingredient Diets 1 2 3 4 5 Fish meal (65 %CP)1 35.8 35.8 35.8 35.8 35.8 Soy bean meal (45%CP) 17.0 17.0 17.0 17.0 17.0 Ground nut cake (48%CP) 19.0 19.0 19.0 19.0 19.0 Yellow corn 19.2 14.4 9.60 4.80 0.00 Discarded cocoa bean meal 0.00 4.80 9.60 14.4 19.2 Cod liver oil 5.00 5.00 5.00 5.00 5.00 Vitamin-mineral premix2 3.00 3.00 3.00 3.00 3.00 Methionine 0.30 0.30 0.30 0.30 0.30 Carboxymethylcellulose 0.70 0.7 0.70 0.70 0.70 Chromic oxide 0.50 0.50 0.50 0.50 0.50 1Values in bracket (crude protein) 2Per Kg of diet: Vit. A 1,000,000 IU; Vit. D3 600,000 IU; Vit. E 12,000 IU, Vit. K315mg; Vit. C 12,500mg; Vit. B1 250mg; Vit. B2 1,750mg; Vit. B6 875; Vit. B12 2,500mg; Ca-Dpantothenate 5000mg, Nicotinic acid 3,750mg; Folic acid 250mg; Co. 24,999mg; Cu 1,999mg; Fe 11, 249mg; Se (Na2SeO3.5H2O) 75mg; I (KI) 106mg; antioxidant 250mg. Table 2. Proximate composition of experimental diets (percent dry matter). Parameter Diets 1 2 3 4 5 Moisture 12.5 11.7 11.3 11.5 11.1 Crude protein 40.2 40.4 40.6 40.4 40.8 Crude lipid 12.2 12.5 12.5 12.3 12.6 Crude fibre 7.50 6.40 6.20 6.20 7.20 Ash 15.8 14.3 14.6 14.4 14.7 NFE1 11.8 14.4 14.8 14.6 13.6 Gross energy (KJ/g) 18.1 18.5 18.6 18.5 18.4 1NFE (nitrogen free extract) = 100- percent crude protein + percent crude Lipid + crude fiber + percent ash) Experimental tanks and feeding trial Fifteen glass tanks filled with 40 L of water were used for the study. The five dietary treatments were replicated three times. The tanks were aerated to maintain the level of dissolved oxygen at 7.5-8.3 throughout the experimental period. The pH and dissolved oxygen levels in the experimental tanks ranged frin 6-8 and 27-30ºC. Healthy juvenile African catfish (11.8±0.68g) purchased from Esabol Fish Farm, Oba-Ile Estate Akure were acclimated for two weeks and stocked at 12 fish per tank. The fish were fed to satiation twice daily between 0800-0900 and 1600-1700 for 70 days. Weight measurements were taken biweekly for assessment of fish performance. Each day before feeding, the fecal matter in the tanks was siphoned and 30 percent of the tank water was replaced every three days to maintain the water quality. Growth performance was calculated after Castell and Tiews (1980) as follows: mean weight gain = final mean weight – initial mean weight; specific growth rate =100 x (loge final weight-Loge initial weight/ culture period in days; feed conversion ratio = weight of feed fed/fish weight gain. Analytical Methods Proximate and mineral analysis of fish samples At the end of the experiment the fish were not fed for 24 h. The catfish were weighed and four fish from each tank were sacrificed for proximate analysis (three replicate analyses per treatment) according to the methods of AOAC (1990). About 2.0 g of the samples were ashed for 48 h at 480ºC. After the ash had cooled to room temperature, 6 mL of HCl was added and the mixture was brought to the boiling point. After cooling to room temperature, another 2.5 mL of 6N HCl was added and the mixture was warmed to dissolve all the solutes. The solution was then cooled and diluted to 25 mL with distilled deionized water. Then the minerals (Mg, Ca, K and Fe) were measured by Atomic Absorption Spectrophotomry (AAS). Phosphorus content was analysed using the Vanadomolybophosphoric acid colorimetric method 4500p with slight modifications. To 3 mL of the diluted solution of the sample, 3 ml of vanadatemolydate reagent was added and the phosphorus concentration was measured spectrophotometrically at 430 nm. Blood analyses After the feeding trial, the fish were starved for 24 h and blood samples were collected by cardiac puncture and put into tubes containing 15 IU of heparin/ml of blood. The blood was centrifuged at 4,000 g for 5 min and the plasma was extracted and stored at -20ºC. Hematological examinations of the red blood cells (RBC), haematocrit (PCV), haemoglobin (Hb), erythrocyte sedimentation rate and the white blood cell counts were carried out using the methods of Svobodova et al. (2006). Statistical analyses Growth, carcass, minerals data and blood parameters were analysed using one-way analysis of variance (ANOVA), followed by Duncan’s new multiple range test (Duncan 1955) at the
14 June 2010 be ascribed to better digestibility and mineralization in fish fed diets with DCM. Also there was a general increase in the gross energy of the diets as a result of inclusion of DCM. The growth performance of the fish (Table 3) showed that DCM can replace up to 75 percent of yellow corn in the diets of African catfish. However, replacement at 25 percent produced significantly better performance than other treatments including the fish fed the control diet. Replacement at 100 percent led to very poor growth performance. Carcass proximate composition (Table 4) showed a decreasing trend in the moisture content of the fish as a result of inclusion of DCM in the diets. There was also a general increase in carcass protein, lipid and ash content attributable to the effect of DCM in the diets. However, while the carcass ash was improved significantly, protein and lipid content of the fish were improved marginally. Table 5 shows that the effect of the DCM on the diets was mostly reflected in the mineral composition of the fish, because the fish that received diets of DCM had significantly higher Ca, P, Mg and Fe than the fish fed the control diet. However, the K content showed a decreasing trend with increasing levels of DCM in the diets. Hence, fish fed the control diet contained significantly higher K than the fish fed other diets. Also, the Ca, Mg and Fe contents of the fish showed an increasing trend with increasing levels of DCM in the diets. The hematological profile of the fish (Table 6) showed no noticeable change related to treatment. There were no significant differences among the treatments for any of the measured parameters. Table 3. Growth performance of African catfish fed on varied levels of discarded cocoa bean meal. Mean values1 Diets 1 2 3 4 5 Initial weight (g) 11.4±0.4 12.3±0.8 11.1±0.6 11.7±0.9 12.5±0.8 Final weight (g) 27.9b±4.8 43.7c±2.1 33.3b±5.0 32.5b 16.7a±0.6 Weight gain (g) 16.4b±4.6 31.5c±2.1 22.2b±5.2 20.7b±4.7 4.16a±0.3 Percent weight gain 143.1b 255.7c 201.7bc 177.1b 33.4a Specific growth rate 1.25b±0.2 1.80c±0.1 1.56bc±0.3 1.44b±0.2 0.41a±0.0 Feed conversion ratio 1.70b±1.1 1.01a±0.1 1.43ab±0.4 1.34ab±0.2 3.27c±0.6 1Means in each row with the same superscript letters are not significantly different (P>0.05) Table 4. Proximate composition of the fish after experiment (g/100 g dry matter) Mean Values1 Diets 1 2 3 4 5 Moisture 9.00b±1.9 4.88a±0.7 4.83a±0.9 4.82a±0.9 4.81a±1.1 Crude protein 64.9a±0.6 65.6a±1.6 65.7a±0.6 65.9a±1.2 65.9a±0.8 Crude lipid 13.2a±0.8 13.4a±1.9 13.5a±1.2 13.4a±2.0 13.7a±0.2 Ash 12.7a±0.8 16.6bc±1.1 17.2c±0.3 15.8b±0.5 16.5bc±0.2 1Means in each row with the same superscript letters are not significantly different (P>0.05) Table 5. Mineral composition of the fish after experiment. Mean Values1 Diets 1 2 3 4 5 Ca (mg g-1) 28.5a±1.9 32.8b±0.7 32.9b±0.9 32.9b±0.6 35.2c±0.2 P (mg g-1) 18.6a±0.0 20.3b±0.0 21.2c±0.0 20.6b±0.1 20.1b±0.0 Mg (mg g-1) 3.01a±0.0 3.88b±0.0 3.88b±0.0 3.89b±2.0 4.02c±0.0 K (mg g-1) 32.0c±0.2 31.6bc±0.1 24.8b±0.1 19.1a±0.5 19.5a±0.1 Fe (µ g-1) 37.0a±0.3 49.5b±1.0 59.3c±0.8 59.4c±1.4 59.5c±1.4 1Means in each row with the same superscript letters are not significantly different (P>0.05) 5 percent level of significance to detect differences among treatment means. Economic estimation A simple economic model of Vincke (1969) was used to estimate the costs of production, the incidence of cost (IC) and benefits and the profit index (PI). The model is based on the relationships between fish weight gain and the cost of feed, and the value of total fish produced and the cost of feed. Hence IC is given as cost of feed/weight gain while PI is defined as value of fish/cost feed. During costing, 50 percent of the cost of yellow corn was assumed for the cost of the DCM to cover expected costs of processing the discarded cocoa bean meal. Results The proximate composition of the experimental diets (Table 2) showed uniformity in all the parameters. The parameters were so closely related that the effect of replacement of yellow corn with DCM was not noticeable. Therefore, the effect reflected on the growth parameters, and especially the mineral composition of the fish could
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