Groupers are highly prized throughout Asia and have traditionally been caught using nets, traps and baited hooks, but overfishing has led to diminishing wild stocks all over the world. As a result, over the last decade there has been a concerted effort to develop the means to culture grouper – both to help relieve pressure on wild stocks and to provide regular quantities of high-quality fish to the market(Frisch, Cameron, Williamson, & Williams, 2016) (Rimmer & Glamuzina, 2019).
While today’s practice of feeding rotifers during the first larval period has allowed for cultivation of various grouper species, the survival rate is usually low and the growth and quality of the larvae varied. To ensure the rotifers have an adequate nutrient composition is not straightforward – they often lack key nutrients such as taurine, vitamin A, Iodine and fatty acids like DHA and EPA. Looking into alternative feed solutions has therefore been a priority.
In the wake of this, several studies have appeared showcasing the potential offered by the application of copepods as feeds for larval grouper. For larval leopard coral grouper (Plectropomus leopardus) a tenfold increase in survival, in addition to more rapid development, was observed (Burgess, Callan, Touse, & Santos, 2019) (Melianawati, Astuni, & Suwirya, 2013). Adding copepods to the diet also quadrupled the survival rate of tiger grouper (Epinephelus fuscoguttatus) (Rimmer, et al., 2011). In addition, growth parameters such as total length, body depth and dorsal and pelvic spine length were positively affected, all in all producing more vigorous larvae.
Despite these results, setting up copepod production units has not been an option for most hatcheries, as they require much work and don’t always produce a steady supply. However, due to companies like CFEED* now supplying the Asian market, copepod eggs can be obtained and hatched on demand in a similar way as Artemia cysts. This has led to a number of commercial hatcheries starting to incorporate copepods into their feeds.