Norbert Zonneveld, Rasyid Fadholi
Red tilapia (phenotypically Orenchromis niloticus) fingerlings, obtained from the Provincial Fisheries Service in East Java, Indonesia, were stocked at 0.125, 1, 4, 12, and 20 fish /ml in 32 m2 stagnant water concrete ponds and fed ad libitum on commercially available pelletized diets containing (on dry matter basis) 28.2 and 28.8% crude protein and 19.0 and 19.1 kJ g-1 energy respectively. Maximum yield of 17.0 kg/pond per 8 weeks (or 5.3 tonnes/ha per 8 weeks) was obtained at a stocking density of 12 fish/m2. while the average individual growth rate was highest for the lowest density. The relative growth rate of the metabolic weight (RGRm) increased linearly with the feed intake expressed as metabolic ration (Rm) and is given by the equation: RGRm = 0.790*Rm - 2.571 (r2 = 0.63). Maximum RGRm values were realized in the first 4 weeks for the lowest densities and ranged between 30.1 and 34.0 g kg-0.8 d-1 (measured over 2-week periods). Maintenance ration was calculated to be 3.25 g kg-0.8 d-1 (or 62.0 kJ kg-0.80 d-1). These values are compared with recalculations of results in the literature. The apparent net protein utilization (NPUa) averaged 42.5% for the 0.125, 1, 4, and 12 fish/m2 treatments. Taking the marketable size of 100 g into consideration, a stocking density of 4 fish/m2 is recommended. © 1991.
Department of Fish Culture and Fisheries, Agricultural University, 6700 AH Wageningen, P.O. Box 338, Netherlands; Faculty of Fisheries, Brawijaya University, Malang, Jl. Mayen Haryono 166, Indonesia
