LABORATORY SURVIVAL, GROWTH, AND DIGESTIVE GLAND HISTOLOGIC FEATURES OF SQUIDS REARED ON LIVING AND NONLIVING FISH DIETS

The effects of non-living diets on the survival, growth, and digestive gland histologic features of the bigfin reef squid (Sepioteuthis less oniana Lesson, 1830) cultured in the laboratory were evaluated during one-half of their life cycle (95 days). Two groups of squids (n = 16 p er group) were held in closed seawater systems with similar water volu me, temperature, salinity, water filtration, and water flow velocities . Food for the control group consisted of live, freely swimming fish ( Cyprinodon variagatus); the test group was trained to grab freshly dea d fish (days 1 to 45) and then thawed, frozen fish (days 46 to 95). Th e two groups were evaluated for differences in (1) food intake, (2) su rvival, (3) growth (wet weight, mantle length, instantaneous growth ra te), (4) morphologic (mantle thickness in four locations, digestive gl and weight), and (5) digestive gland histologic features (indices for nuclear density and relative vacuolar density). Unexpectedly, no signi ficant differences were found between the two groups. Mean wet weight increased from 32.1 g to 342.9 g for the control group and from 58.6 g to 372.0 g for the group fed dead food. The results demonstrate that laboratory-cultured squids can survive and grow when fed dead fish (fr esh or frozen) as well as live fish without adverse effects on growth, survival, or digestive gland histologic features.