Evaluation of different supplemental feeds for milkfish ( Chanos chanos) reared in brackishwater ponds

Abstract

The effects of supplemental feeding on milkfish growth, production, survival, water quality, and economic benefits in brackishwater ponds were evaluated by comparing a rice bran diet, containing 11.3% protein, and two pelleted diets, containing 22.0% and 27.4% protein, with an unfed control. Four 800-m 2 tide-fed ponds, subdivided into quarters, were used. Each treatment was replicated in four random pond compartments. Milkfish with initial average weight of 1 g were stocked at 8000/ha and feeding commenced when the average weight and standing crop were 57 g and 417 kg/ha, respectively. All supplemental feeds significantly ( P<0.05) increased growth and production over the unfed control. Feeding diets containing 22.0% and 27.4% protein resulted in 35.3% and 46.7% higher net profits, respectively, whereas feeding rice bran resulted in a 34.4% lower net profit when compared to the unfed control. The growth of milkfish became significantly slower ( P<0.01) than those fed the 27.4% protein diets when the standing crop of unfed and rice bran-fed fish reached 535 kg/ha and fish fed the 22.0% protein diet reached 972 kg/ha. Survival was not significantly different among the treatments. The concentration of metabolites in the culture water for all treatments was low but a significant increase ( P<0.05) in level of total carbon dioxide and nitrite-nitrogen was observed as biomass increased.