Commercial aquaculture of marine ornamental fishes disproportionately targets demersal spawners with simple husbandry requirements

Marine aquaculture currently supplies over half of the fish consumed worldwide, mostly involving pelagic spawners. In contrast, marine ornamental fish aquaculture appears to rely more on demersal spawners, which may offer management advantages, such as parental care, larger eggs and larger larvae at hatching. We assessed whether ornamental fish aquaculture is biased towards species with simpler husbandry practices. Six reproductive, embryonic, and larval development traits were analyzed: sexuality, spawning type, egg size, duration of embryonic development, larval size at hatching and duration of larval development. Data were compiled for 527 globally traded ornamental species, including both mass-cultured and non-mass-cultured species. Sexuality showed no trend among mass-cultured species (n = 80), but all other traits indicated that mass-cultured species tend to be demersal spawners that produce larger eggs with longer embryonic development, and have larger larvae at hatching. Duration of larval development was not correlated with the preference for a species in the ornamental aquaculture, likely due to the limited sample size. Demersal spawning facilitates aquaculture: larger eggs are easier to handle, longer embryonic periods yield more developed larvae capable of feeding on larger prey, and larger newly hatched larvae improve survival and reduce production costs. While protocols have been established for some pelagic spawners, most are rarely mass-cultured, indicating that larviculture is the main bottleneck for large-scale production. Within the context of sustainable marine ornamental aquaculture, technological advances are needed to establish protocols for high-value and endangered species, enabling large-scale production and offering viable alternatives to reduce further impacts on wild populations.