Growth Trend and Food Regime of Juvenile Pikeperch (Sander lucioperca) in Earthen Ponds

This study was carried out during 45 days trial in Siahkal Dr. Yousefpour Marine Fishes Restocking and Genetic Conservation Center. Food habits of juvenilepikeperch were studied up to 1 g body weight in four 4 ha earthen ponds. Sampling of larvae and juveniles was carried out every 15 days interval, and totally, 320 fish were caught from the ponds. The gastrointestinal tract contents of sampled fish were examined. The gut contents of juvenilepikeperch included rotifer, daphnia, cyclops, and chironomid. In larval stage, rotifer and daphnia were main food items. In the second sampling period (day 30), rotifer and daphnia were the main foods items, while cyclops naupli were consumed as marginal foods. At the end of the experiment, daphnia, cyclops and chironomid were among the main foods and rotifer was an occasional food. The results showed that the biomass of live food in ponds increased at the beginning of the rearing period, but at the end it showed a descending trend. Growth indices such as growth rate (GR), specific growth rate (SGR), and condition factor (CF) were measured at each sampling. The results showed that GR increased with increasing weight and length of fish during the rearing period. However, the reduction of SGR and CF at the end of the period was due to the loss of live food in the ponds. According to the present study, live food at different sizes during the experiment period led to acceptable fish growth. Fish are eager to feed larger size (chironomid and daphnia) of live foods after larval stage with reduce consumption of rotifer. Therefore, live food production through fertilization and ponds enrichment is economical approach and can help to manage the ponds for growing and producing higher-quality juvenilepikeperch in a shorter period.