THE EFFECTS OF SEMI-PURIFIED DIETS ON GROWTH AND CONDITION OF SEPIA-OFFICINALIS L (MOLLUSCA, CEPHALOPODA)

The effects of five different surimi diets (fish myofibrillar protein concentrate) on growth and condition of Sepia officinalis were evaluat ed in terms of individual growth using different morphometric and bioc hemical parameters. A casein supplemented surimi diet produced signifi cant growth (instantaneous growth rate 0.4-0.8% body weight). The dige stive gland-to-body weight ratio increased and the cuttlebone-to-body weight ratio decreased significantly in relation to instantaneous grow th rate. The RNA content of mantle muscle increased significantly, whi le the DNA content of mantle muscle did not change in relation to inst antaneous growth rate. Mantle muscle protein content was depleted in c uttlefish with instantaneous growth rate less than or equal to 0. No c ompensatory food consumption, food conversion or growth was observed f or cuttlefish fed surimi;diets after refeeding them with a natural die t (thawed raw shrimp). Digestive gland and cuttlebone-to-body weight r atios, and RNA content in mantle muscle could be used as short-term in dicators of instantaneous growth rate and condition of cuttlefish. Man tle muscle protein content could be used as a long-term indicator.