Effects of aeration on the production of Heterobranchus bidorsalis fingerlings at varying stocking density in outdoor concrete tanks

Abstract

The effects of stocking density with or without aeration on survival and growth of Heterobranchus bidorsalis fry were examined under outdoor management systems. The fry were held at six stockin densities of 250 fry/m³, 500 fry/m³, 750 fry/m³, 1,000 fry/m³, 1,250 fry/m³ and 1,500 fry/m³.  There was no significant difference (P > 0.05) in the mean weight gain and specific growth rate of fry held at the different stocking densities with aeration. However, the mean weight gain and specific growth rate decreased as stocking density increased. Average final weight of fish was significantly (P < 0.05) affected by aeration.  Relative to initial body weight, fish growth in unaerated tanks was lower in final weight than in aerated tanks. Development of “jumpers” was significantly affected by aeration. There were significant differences in the survival of H. bidorsalis fry held at the different stocking densities.  Highest survival was obtained at stocking density of 250 fry/m³ while sticking density of 1,500 fry/m³ gave the lowest survival in both aerated and unaerated treatments. Fry held at 500 fry/m³ gave the optimum stocking density (level) in aerated tanks while stocking level of 250 fry/m³ is ideal for optimum growth and development of fry in the outdoor concrete tanks without aeration.