Digestive enzymes of Anarhichas minor and the effect of diet composition on their performance

The effect of feeding two different diets, containing 38 and 45% protein and 35 and 28% lipid, respectively, on growth as well as performance of the digestive proteases (total protease at pH 1.5, 7.0, 9.0 and 10.0) and carbohydrases (total carbohydrase, a-amylase and a-glucosidase) of a new candidate species for aquaculture, the carnivorous spotted wolffish Anarhichas minor (Teleostei, Anarhichadidae), was investigated. No significant growth differences were observed when feeding high protein (HP) or low protein (LP) levels (P > 0.05), although the LP group exhibited slightly higher protease activity and capacity (P > 0.05), mostly at the anterior end of the intestine and at alkaline pH. Carbohydrase levels were generally low, apart from a-glucosidase, which was significantly increased for the HP group (P < 0.05). Implications concerning the performance of digestive enzymes under varying dietary macronutrient levels and effects of digestive enzyme activity on the formulation of efficient artificial diets for carnivorous fishes are discussed in this study. © 2006 The Fisheries Society of the British Isles.