The potential of tropical paracalanid copepods as live feeds in aquaculture

Abstract

The small calanoid copepods Bestiolina similis and Parvocalanus crassirostris (Paracalanidae) are compared to Acartia sinjiensis, a species of the copepod genus most commonly cultured to provide larval diets for tropical snappers and groupers. All species are easily maintained in culture, though cultures of Acartia spp. are easier to establish because of the positive phototactic behaviour of this genus. B. similis and P. crassirostris are smaller than A. sinjiensis, and consequently, their developmental stages are more suited to larval fish requiring small prey items. In addition, siphon-avoidance experiments indicated that adults of these species were more vulnerable to predation, though this was not the case for juvenile copepods. Egg production was maximised with larger algal cells, especially Rhodomonas sp. and Heterocapsa niei: B. similis fed H. niei achieved the highest egg production rates (48 eggs female-1 day-1). Lipid composition of all species was low and variable (11–26 mg g-1) under our culture conditions, in contrast to results from temperate copepod species or from wild-caught copepods. All three species studied had DHA/EPA/ARA ratios that met or exceeded those recommended for marine larval fish feeds (DHA/EPA/ARA-14:3:1, 20:9:1 and 25:6:1 for A. sinjiensis, P. crassirostris and B. similis, respectively). On the basis of size of developmental stages, susceptibility to predation, growth rate and nutritional composition, B. similis was the best candidate for larval fish diets.