In intensive fish culture, fish are generally fed with high protein diets. The nutrient-rich wastes derived from feeding are often directly or indirectly released to the surrounding environment, becoming a source of pollution. The wastes from intensive fish culture can be used for culturing filter-feeding fish species such as Nile tilapia (Oreochromis niloticus) at low cost. Dual integrated culture systems, namely cage-cum-pond and pen-cum-pond culture systems, have been developed to maximize fish production and profitability from given inputs and to minimize the environmental impact of intensive fish culture.
Integrated cage-cum-pond culture system
n Extending open-pond fish culture for sometime after harvesting caged fish can further reduce nutrient loading in pond effluents.
Example 1: Catfish/tilapia integrated cage-cum-pond culture
Hybrid catfish (Clarias macrocephalus x C. gariepinus) are
usually cultured intensively using high protein diets, while Nile tilapia (Oreochromis
niloticus) are cultured semi-intensively in fertilized ponds. These two
species are used in the following example.
Example 2: Large/small tilapia integrated cage-cum-pond culture
Nile tilapia is commonly grown in semi-intensive ponds based on fertilizers
or in integrated systems with livestock. Size at harvest, under such systems,
usually averages 200-300g in five months. Larger Nile tilapias (around 500 g)
fetch a much higher price than smaller ones
(<300 g) resulting in a trend to culture bigger fish in intensive culture
systems. Supplemental feeding of Nile tilapia, starting at 100-150 g in size, is
the most effective way to produce large-sized fish. In this example, large
tilapia fingerlings are fattened in cages with high protein diets, while small
fingerlings are nursed in open ponds by utilizing natural foods derived from the
cage wastes.
To optimize the system:
l Fatten large-size tilapia (approximately 140 g) to more than 500 g or bigger, in two cages in a pond with a surface area of 300-400 sq m and water depth of 1.2 m.
l Small-size tilapia (approximately 20 g) can be nursed to around 140 g size in open-ponds by utilizing cage wastes. These are removed every three months to restock the cages.
Integrated pen-cum-pond culture system
l It is a system in which a fish pond is partitioned into two compartments using netting material.l The fed fish and filter-feeding fish are separated to utilize high protein diets more effectively and the natural foods derived from feeding wastes.
Example: Catfish/tilapia integrated pen-cum-pond culture
l Earthen ponds with surface area of 200 sq m and 1 m water depth are
partitioned by 1-cm mesh plastic net into
two compartments: 1/3 for hybrid
catfish and 2/3 for tilapia.
l Catfish are fed with commercial pelleted feed.
l In the first month, fertilize the tilapia compartments weekly using urea and TSP at rates of 28 kg N and 7 kg P/ha/week.
References
Diana, J.S., C.K. Lin and Y. Yi. 1996. Timing of Supplemental Feeding. Journal of the World Aquaculture Society 27:410-419.
Lin, C.K. 1990. Integrated Culture of Walking Catfish (Clarias macrocephalus) and tilapia (Oreochromis niloticus). In: R. Hirano and I. Hanyu (eds.), The Second Asian Fisheries Forum. Asian Fisheries Society, Manila, pp. 209-212.
Lin, C.K. and J.S. Diana. 1995. Co-culture of Catfish (Clarias macrocephalus x C. gariepinus) and Tilapia (Oreochromis niloticus) in Ponds. Aquatic Living Resources 8:449-454.
Yi, Y., C.K. Lin and J.S. Diana. 1996. Effects of Stocking Densities on Growth of Caged Adult Nile Tilapia (Oreochromis niloticus) and on Yield of Small Nile Tilapia in Open water in Earthen Ponds. Aquaculture 146:205-215.
Yi, Y. and C.K. Lin, 2000. Integrated Cage Culture in Ponds: Concepts, Practice and Perspectives. In: I.C. Liao and C.K. Lin (eds.), Proceedings of the First International Symposium on Cage Aquaculture in Asia. Asian Fisheries Society, Manila, pp. 217-224.
Yi, Y., C.K. Lin and J.S. Diana, in press. Integrated Recycle System for Catfish and Tilapia Culture. In: Eighteenth Annual Technical Report. Pond Dynamics/Aquaculture CRSP, Oregon State University, Corvallis.
