Cage culture, the practice of rearing fish in cages, can be applied in existing bodies of water that cannot be drained or seined and would otherwise not be suitable for aqua-culture. These include lakes, large reservoirs, farm ponds, rivers, cooling water discharge canals, estuaries and coastal embayment’s. In Kenya, tilapia are among the most suitable fishes for cage culture.
Species selection
The most appropriate species or strains of tilapia for cage culture are Tilapia nilotica (Nile Tilapia), T. aurea (blue Tilapia and hybrids between these species and strains. The choice of a species for culture depends mainly on avail- ability, legal status, growth rate and cold tolerance. Tilapia can be cultured at high densities in mesh cages that maintain free circulation of water. Cage culture offers several important advantages. The breeding cycle of tilapia is disrupted in cages, and therefore mixed-sex populations can be reared in cages without the problems of recruitment and stunting, which are major constraints in pond culture. Eggs fall through the cage bottom or do not develop if they are fertilized. (Reproduction will occur in cages with 1/10-inch mesh or less, which is small enough to retain eggs.)
Other cage advantages include:
- Flexibility of management,
- Ease and low cost of harvesting,
- Close observation of fish feeding response and health,
- Ease and economical treatment of parasites and diseases,
- Relatively low capital investment com- pared to ponds and
Some disadvantages are:
- Risk of loss from poaching or damage to cages from predators or storms,
- Less tolerance of fish to poor water quality,
- Dependence on nutritionally-complete diets,
- Greater risk of disease
