MANAGEMENT INDUCED CHANGES IN POND WATER QUALITY AND GROWTH PERFORMANCE OF GOLDFISH, Carassius auratus (L.), IN TWO 11-WEEK GROWTH EXPERIMENTS CONDUCTED DURING THE SUMMER AND WINTER SEASONS

To assess the seasonal influence on the growth performance of goldfish, Carassius auratus (L.) in earthen ponds maintained under different production management regimes, two 11-week growth experiments were conducted during two different seasons (summer and winter) under tropical conditions in India. Weight gain, survival rate and fish deformities were compared among four management regimes in each season: (1) fish larvae fed with live zooplankton (LF); (2) direct fertilization with poultry manure (PM); (3) direct fertilization with cow dung (CD); (4) a control system (C), where a commercial diet containing 32% crude protein was applied. The LF treatment produced significantly higher weight gain and survival rate of goldfish (P < 0.05) in both the trials through maintenance of better water quality and greater abundance of zooplankton in the system. Fish deformities were highest in the C treatment in both the experiments. Water temperature averaged 27.5oC and 16.2oC, respectively, in the summer and the winter trials. Average weight gain and survival rates of goldfish achieved during the winter trial were considerably lower than the summer trial (P < 0.05).