PHYSICOCHEMICAL PARAMETERS AND PLANKTON COMPOSITION ON MONO-SEX NILE TILAPIA PRODUCTION IN PONDS

The effect of physicochemical parameters and plankton composition on mono-sex Nile Tilapia production in ponds was investigated in three fish farms for twelve weeks from March to May, 2012. The physic-chemical parameters were found to be respectively, temperature=27.14-27.20⁰C, transparency=22.15-24.64cm, dissolved oxygen=6.59-6.83mg/l, pH=7.94-8.01, free carbondioxide=5.46-12.78mg/l, total alkalinity=44.37-56.84mg/l, chemical oxygen demand (COD)=25.67-42.65mg/l, biological oxygen demand (BOD)=0.76-4.86mg/l. The phytoplankton population in three different farms was found to be consisting of 19 genera including 4 dominant families, Bacillariophyceae, Chlorophyceae, Euglenophyceae, Cyanophyceae, and nine genera of zooplankton under the families of Rotifera and Crustaceaan. Phytoplankton and zooplankton showed inverse relationship between them in growth. Chlorophyceae was dominant all over the experimental period but Bacillariophyceae showed highest rate of feeding by fish during gut analysis. There were no significant variation among the survival of fish in different farm and ranged were limited to 93.34 to 97.13%. This study showed that fish yield was dependable on the quality and management of ponds water characteristics. The highest production found in T₂ was 2175.68kg/ha/12weeks and 80 fish per decimal showed best stocking density for optimum utilization of the natural food.