Table 6. Yields of tilapia (Sarotherodon aureus) from ponds receiving cow manure with
and without supplementary feeding with grains (after Moav et al. 1977).
Stocking Average Average Daily Daily
density initial weight final weight weight gain Survival yield
( fishlha) (9) (g) (g/fw (kg/ha)Ponds receiving only cow manure
Tilapia (^1) 3,320 97 430 2.6
Tilapia 2 1,680 21 221
91.5 8.9
1.6
Ponds receiving cow manure + supplementary feed
Tilapia 1 3,320 97 416 2.5
Tilapia 2 1,680 21 220
88.5 8.5
1.6
*Handllaxed. all-male
Lovshin and Da Silva (1975) report that ponds stocked with all-male
hybrid tilapia at a density of 8,000Fa (average weight 25 g), when manured
with 500 kg/ha/wk chicken manure gave an average yield of 1.35 t/ha after
189 days and an average weight at harvest of 186 g.
Fresh manure disintegrates in water into colloidal particles which are
attacked by bacteria and readily incorporated in the food web. Integrated
farming systems where animals are kept over fish ponds and their wastes fall
directly into the pond usually result in high fish yields. Here again, tilapias
are very responsive. Van der Lingen (1959~) cultured ducks (1 duck/8.3m2)
on a pond stocked with tilapias (S. mossambicus, S. macrochir and T.
rendalli). He obtained a yield of 3.48 t/ha, of which more than 40% were
over 225 g. Culture experiments carried out in Israel also showed increased
yields of S. aureus in a polyculture (H. Barash pers. comm.).
The integration of tilapia culture and pig fattening has also given good
results. Lovshin and Da Silva (1975) constructed pigsties on the borders of
0.01 ha ponds to give manure loadings of 70 pigs/ha of pond. The pig
manure was washed daily into the ponds. -were stocked with
8,00O/ha tilapia (all-male hybrids of 25 g) and were harvested after 189 days
at an average weight of 205 g. The fish yield was 1.5 t/ha. The only supple-
mentary feed was that supplied to the pigs. 1
Feeding
Tilapias larger than 4 to 5 cm take supplementary feed readily (Le Roux
1956; Bishai 1962; Huet 1970). Meschkat (1967) lists many feedstuffs
used in tilapia culture such as plants, copra wastes, cotton seeds, etc. No
information is given, however, on the effectiveness of these feedstuffs. It
seems that some feeds are less effective than others. Experience in Israel has
shown that whole sorghum grain does not affect the growth of S. aureus
much, either because they are not eaten or have a low nutritional value. A