| Abstract | Two experiments were conducted with walking catfish ( clar1as
macrocephalus) at stocking densities of 5o, 1oo and l5o fish/ m3
in an out door concrete recirculation system linked to tilapia
ponds with a stocking density of 2 fish/m3. Clarlas were fed ad of
libtum with a low cost feed and nutrients from the waste water
of Clarias culture was the only input into tilapia ponds. Growth,
food conversion, survivals and related water chemistry was
evaluated during the two experiments. Fish with mean initial
weights of 1.14 ±0.02, 1.24 ±0.02 and 1.22 ±0 .01 ( g ) in
treatments with 5 0, 100 and 150 fish/m 3 in Experiment l reached
mean final weights of 7.69±0.17, 5. 11 ±0.5 1 an d 6.74 ±0.89 (g ),
respectively in 30 days culture period. The corresponding food
conversion rations and surviva1s were 1 . 1 4 ± o . o 2 , 2 .-6 9 ± o . 3 7 , 2 . 9 7
±1.08, and 97.8 ±0 .7, 30.8 ±4.5, 36.2 ± 10.4 (%), respectively.
In Experiment 2 a similar trend of better growth, conversion and
survivals was observed for fish at a density of 50/m3. Fish with
mean initial weights of 0 . 83 ±0 . 01, 0.78 ± 0 . 01 and 0.82 ±0.01 ( g )
in treatments with 5 0, 100 a nd 150 /m 3 attained mean final
weights of 12.10 ±0.17, 9.58 ± 0 .51 and 7 . 91 ±0.89 (g ),
respectively in 56 days culture period. The corresponding food
conversion and survivals were 1. 30 ±0.03, 1.62 ±0 .10, 1.94 ±0.14
and 97.3 ±2.2, 83.6 ±4 .l and 82.3 ±8.7 (%), respectively. In
both experiments, walking catfish in density of 50 fish/m3 showed
excellent growth, food conversion and survivals. A mean initial
biomass of 6.04 (l{ g ) tilapia in the three ponds attained a final
biomass of 14 .25, 12.8 and 11.8 (k g ), respectively utilizing the
wastes from the Clarias culture. Tilapia receiving wastes from
Clarias tanks with 150 fish/m 3 attained high mean final weight.
Total phosphorous and total nitrogen present in the waste waters
of Clarias culture had fertilization effect on the earthen ponds.
Loading rate of total phosphorous and total nitrogen into earthen
ponds in Experiment 1 and 2 was in the range of 0.002 - 0.003 and
0.023 - 0.037 g/day/m3 , respectively. |