Evaluation of commercial catfish, tilapia and salmonid diets for growth promotion of white suckers

In an attempt to identify appropriate diets for use in intensive baitfish culture, the efficacy of three commercial diet formulations, a high-protein, high-lipid, low-carbohydrate diet [a semi-moist salmonid diet (SD)] and two low-protein, low-lipid, high-carbohydrate diets [a catfish diet (CD) and a tilapia diet (TD)] on growth performance of juvenile white suckers, Catostomus commersoni, was examined. All three diets permitted growth during the 16 week trial. The SD promoted highest growth and somatic protein and lipid deposition, whereas the CD and TD formulations promoted markedly higher accumulations of glycogen in the carcass and liver. The high hepatic glycogen content was associated with an elevated hepatosomatic index in the CD- and TD-fed groups. Plasma T3 levels were lower in the CD- and TD-fed groups, possibly a response to the low dietary protein or indicative of dietary insufficiency in these fish. Of the three diets evaluated, the SD was considered to be the best in terms of the growth performance parameters measured, and offers an economical and appropriate diet for intensive culture of juvenile white suckers.