the aim of this study was to show the effect of four feeding regimes on thyroid hormones concentrations, growth performance and food coefficient in rainbow trout applied through 4 treatments and 3 replications in winter 2006. in this research, samples of rainbow trout with an initial mean weight (so) 47.19±0.42 used in each rearing unite. fish were fed twice a day ad libitum as follows: treatme...