World Aquaculture March 2019

WWW.WA S.ORG • WORLD AQUACULTURE • MARCH 2019 65 TABLE 1. Descriptive statistics of silver catfish from Epe Lagoon, Nigeria. Biometric indices Min Max Mean +SD Weight (g) 136 644 219 26 Fork length (cm) 22.5 35.4 24.8 0.7 Total length (cm) 26.7 40.8 29.7 0.8 Ovary weight (g) 27 73 34 2.7 Fecundity (ova) 2545 8415 2981 345 Ova/gram ovary 93 115 87 Broodstock Collection and Spawning Wild broodstock were collected from Epe Lagoon (6 o 35’ 20” N, 3 o 43’ 33” E), Lagos State, Nigeria. Courtship pairs were targeted from the longline fishery (Fig. 2). Collected pairs were transported to a wet lab at Lagos State University and held in black 27-L breeding tanks prior to treatments. Twenty gravid silver catfish females were sampled from January to February 2015 from bamboo receptacles on longlines in Epe Lagoon, Lagos. Standard biometric indices such as weight, standard length, fork length and total length were measured (Table 1). Gravid pairs were induced to spawn or allowed to spawn naturally. Gravid breeding pairs were provided with or without receptacles to test the widely held belief that silver catfish will only breed in one (Fig. 3). Fertilized eggs were collected from tanks with and without receptacles and from pairs with or without spawning induction. Silver catfish eggs were deep brown to golden in color (Fig. 4). Spawned eggs were collected and then incubated for five days in McDonald hatching jars (Fig. 5). Eggs and hatchlings were easily overwhelmed by fungal growth, which posed an early challenge in the study. Hatchlings carry their yolk sac for 8-12 days before requiring exogenous feed. D evelopment of fish species other than African catfish Clarias gariepinus is needed to support and increase the daily fish protein intake by the African populace. Silver catfish Chrysichthys nigrodigitatus (Fig. 1) has great aquaculture potential in Africa (Erondu 1997) and is also considered a valuable source of nutritious protein (Abowei and Hart 2008). It is well appreciated in a number of African countries and is highly commercialized, with fish marketed fresh, smoked or dried. Silver catfish belongs to the family Claroteidae and is widely distributed in fresh and brackish waters inWest Africa (FAO 1969, Holden and Reed 1991, Risch and Vreven 2007). Growth is dependent on factors that include species, age, genetic potential, water temperature, health, and quantity and quality of food. A suitable nutritionally balanced feed is the basic requirement for growth and survival of fish larvae (Srivastava et al . 2012). The nutritional and water quality requirements of the early life stages of silver catfish when reared indoors must be established to promote commercial aquaculture of the fish. This article describes research to determine the possibility of rearing silver catfish fry in a controlled indoor environment and to develop a protocol for its mass commercial production. Protocol for Breeding and Hatchery Production of Silver Catfish Fry H.A. Fashina-Bombata, E.P. Anwa-Udonduiah, A.M. Hammed, F.G. Owodeinde, A.A. Jimoh, P.E. Ndimele, A.M Taiwo and Z.Y. Yeni FIGURE 1. Silver catfish Chrysichthys nigrodigitatus . FIGURE 2. Collection of silver catfish broodstock in bamboo used in longline capture fisheries. ( C O N T I N U E D O N P A G E 6 6 )