56 DECEMBER 2015 • WORLD AQUACULTURE • WWW.WAS.ORG The Brazilian native, tropical fish tambaqui Colossoma macropomum is the second-largest scaled fish in the Amazon River basin. Tambaqui meat is well-appreciated locally and in all states of Brazil. Capture production of tambaqui has been stable at about 4,000 t since 2008 (MPA 2011). Tambaqui aquaculture has made a great contribution to the supply of this fish for consumption in the Amazonian region. Most (24 of 27) Brazilian states have been involved in tambaqui aquaculture in recent years (Santos et al. 2013). Brazilian inland aquaculture production increased by 38 percent from 2010 to 2011 to a total of 544,490 t. Brazilian tambaqui production has grown in recent years, driven by expansion in aquaculture, with total production at 111,084 t in 2011 (MPA 2011), representing 20.4 percent of total Brazilian freshwater aquaculture production and the second most in national rankings after tilapia. Tambaqui are reared in diverse systems and environments, such as lakes, reservoirs, tanks, on-farm irrigations canals, storage dams, ponds and cages. In the northeast of Brazil, the main tambaqui farming system is pond culture. Pond production requires a higher technological level compared to cages. The rapid growth of inland aquaculture for tambaqui in cages shows that it is a relatively easy-to-achieve type of aquaculture in developing countries when compared with pond culture because it requires a lower initial investment (70 percent less than conventional farms) and is fast and easy to install and start production. The benefits of growing fish in cages are reduced physical space needed for rearing, greater control and efficient use of feed, decreased production costs, higher productivity without increasing area and greater ease at harvesting. Cages enable the use of existing water bodies and the northeast of Brazil has many such bodies. Rearing of tambaqui in cages may be a viable alternative to fish production in community lakes and dams designed to drain and store rainwater for domestic supplies, irrigation and animal consumption, thereby allowing integrated multiple use of existing water in undrainable farm dams. To expand and create new investors in cage culture, more Production Performance of Tambaqui in Small Cages Carlos Alberto Da Silva studies are needed about management practices, better nutrition and testing of stocking densities. Stocking density is considered a critical factor in production due to its influence on survival, fish growth, yield and water quality. To maximize production and profitability, ideal stocking densities need to be determined for each fish species and stage of development. The aim of this study was to evaluate the production of tambaqui in cages to a market size of ~1 kg at different stocking densities in a lake supplied by rainwater. The experiment was conducted in a 0.55-ha lake located at Embrapa Coastal Tablelands in Aracaju, Sergipe (Figs. 1 and 2). Lake water depth ranged from 1.4 to 2.5 m according to season. The lake did not have any designated use, fish populations and aquatic vegetation at the beginning of the experiment. The trial had two consecutive phases: a nursery phase to test densities of 50, 100, 200 and 300 fish/ m3 for tambaqui that were cultured for 98 days (initial mean weight of 0.35 ± 0.02 g) and a grow-out phase to test densities of 20, 40 and 60 fish/m3 for tambaqui that were cultured for 270 days. The experiment was carried out using twelve floating 1-m3 cages spaced 1 m apart with a metallic mesh size of 20 mm and covered with anti-bird plastic screens (Fig. 3). During the nursery phase, nylon 4-mm mesh was placed into the cage to prevent escape of fingerlings. In the nursery phase, fingerlings were fed with commercial extruded feed for omnivorous fish with crude protein contents of 40 and 36 percent and different particle sizes (powder, 1.7 mm and 3 mm), offered four times per day (700, 1000, 1300 and 1600 h) six days a week. As fish grew, the protein content of feed was reduced and feed size was increased. The daily feeding rate during the nursery phase ranged from 15 to 6 percent of fish body weight daily. Immediately after the end of the nursery phase, the grow-out experiment began with tambaqui juveniles (average weight = 73.8 ± 2.5 g) randomly selected from the nursery phase study. In the growout phase, tambaqui were twice daily (900 and 1600 h) six days a week with an extruded ration commercial for omnivorous fish with FIGURE 1. Location of the pond used to evaluate tambaqui cage culture in the state of Sergipe in northeast Brazil. FIGURE 2. The lake (0.55 ha) in Embrapa Coastal Tablelands used for cage culture of tambaqui. FIGURE 3. Experimental 1-m3 cages used for production of tambaqui.
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