Assessment of compensatory growth in channel catfish Ictalurus punctatus R. and associated changes in body condition indices

A feeding trial was undertaken to evaluate compensatory growth in channel c atfish and to chronicle the changes in body condition associated with the i mposed feeding strategy. Four 1200-L circular tanks were each stocked with approximately 600 fingerling channel catfish (mean initial weight 32 g). Tw o tanks represented control fish which were fed to apparent satiation once daily throughout the trial. The two remaining tanks of fish were unfed for 4 wk and subsequently refed daily to apparent satiation for the following 1 0 wk in order to elicit a compensatory growth response. Fish fed to apparen t satiation during the first 4 wk of the trial had a 41% increase in body w eight, while the fasted fish decreased in weight by 20%. During the subsequ ent refeeding period, previously unfed fish were not able to increase growt h rates sufficiently to overcome weight loss imposed by the 4-wk feed restr iction. However, after 8 wk of refeeding, total increase in body weight of the previously unfed fish was 179% of initial weight and similar to that of control fish which gained 231% of initial weight. Hepatosomatic index (HSI ) and condition factor decreased rapidly during the fasting period and incr eased rapidly to control levels during subsequent refeeding. The intraperit oneal fat (IPF) ratio and muscle ratio responded more slowly to feed restri ction with IPF ratio decreasing consistently after 2 wk of feed restriction . Muscle ratio showed little effect from the 4-wk period of feed deprivatio n. It appears that not feeding channel catfish fingerlings for 4 wk is too long to induce a compensatory growth response that is optimal for aquacultu re; however, HSI may be the index of choice for detecting when refeeding sh ould begin to maximize compensatory growth.