Mono culture of the African catfish can be done when suitable feed, with a high protein content (including animal protein) is available.
The stocking rate depends on the marketable size desired and varies from 2 to 10 fingerlings per square meter, corresponding to a marketable size fish of approximately 500 and 200 g respectively after 6 month. Higher stocking densities are not recommended as adverse water conditions at the end of the production cycle are difficult to manage.
Feeding with a balanced composed feed is a prerequisite for intensive mono culture of the African catfish. The feed should contain 30–35 percent digestible protein (about 40–50 percent crude protein) and 2500–3500 kcal digestible energy/kg feed (about 3500–4500 crude energy/kg feed). The feed is distributed two to three times a day in equal portions.
Some biological data on Mono culture of the African catfish is presented in Table 3.
Table 3 Biological data on monoculture of the African catfish, density 10 m2, mean temperature 25–27 °C.
Week | Mean body weight (g) | Survival (%) | Biomass (kg/100 m2) | Feeding rate (%/biomass/day) | Feed (g/100 m2/day) |
0 | 1 | 100 | 1 | 10 | 100 |
2 | 5 | 70 | 3.5 | 7.5 | 250 |
4 | 10 | 65 | 6.5 | 4.5 | 300 |
6 | 18 | 60 | 10.8 | 4.0 | 400 |
8 | 27 | 60 | 10.2 | 3.3 | 525 |
10 | 36 | 60 | 21.6 | 3.0 | 650 |
12 | 52 | 55 | 28.6 | 2.7 | 775 |
14 | 65 | 55 | 35.7 | 2.6 | 900 |
16 | 79 | 55 | 43.4 | 2.4 | 1025 |
18 | 102 | 50 | 51.0 | 2.3 | 1150 |
20 | 130 | 50 | 65.0 | 2.1 | 1350 |
22 | 160 | 50 | 80.0 | 1.9 | 4500 |
24 | 200 | 50 | 100.0 | 1.8 | Harvest |
Source: Janssen, 1987
After about six month the pond can be harvested and net production of 9–16 t/ha/year can be obtained.
The major problems of intensive monoculture of the African catfish are; water quality and predation
Overfeeding of the fish will result in adverse environmental conditions (low oxygen, high ammonia, high suspended solids, etc). Adverse water conditions often coincides with dense phytoplankton blooms followed by a scum of phytoplankton at the surface of the pond. This will cause low oxygen levels at night and pre-dawn. Flushing of the pond and reduction of the feeding level is the only remedy
Predation is another major problem in intensive farming of the African catfish and in Kibos farm high predation can be expected by the predation through birds.