Housing, Husbandry and Welfare of a “Classic” Fish Model, the Paradise Fish (Macropodus opercularis)

Thanks to its small size, external fertilization and fecundity, over the past four decades, zebrafish (Danio rerio) has become the dominant fish model species in biological and biomedical research. Multiple lines of evidence, however, suggest that the reliance on only a handful of genetic model organisms is problematic, as their unique evolutionary histories makes them less than ideal to study biological questions unrelated to their historically contingent adaptations. Therefore, a need has emerged to develop novel model species, better suited for studying particular problems. The paradise fish (Macropodus opercularis) has a much more complex behavioral repertoire than zebrafish and has been a favored model animal in ethological research during the last decades of the previous century. We believe that with currently available, easily adaptable genetic toolkits, this species could be easily developed into a popular model of behavioral genetics. Despite its earlier popularity, however, the description of a detailed housing and husbandry protocol for this species is still missing from scientific literature. We present here a detailed description of how to raise and breed paradise fish successfully under laboratory conditions, and also discuss some of the challenges we faced while creating a stable breeding population for this species in our facility.

Comparative study on spawning success of paradise fish (Macropodus opercularis) using synthetic hormone and natural simulation

Synthetic hormones are widely used for induced breeding with significant successes. This study compared spawning successes in paradise fish (Macropodus opercularis) using synthetic hormone (Ovaprim) and natural simulation in glass tanks (0.3m x 0.6m). The experiment was conducted in two parts using two males and two females brood fish. The weights of the fish were between 4.0 and 5.0g for the males and 5.0 and 6.0g for the females. For the induced spawning, Ovaprim was injected intramuscularly according to the fish body weight after which they were left to spawn. The group on natural spawning were not induced by any hormone. Hatching of the eggs occurred within 48 hours at a temperature of 28.80C. Total number of eggs obtained by artificial and natural breeding were 430 and 322eggs respectively. Percentage fertilization in artificial breeding was 63.26% while 41.93% was recorded in natural breeding. Fry were raised on compounded diet for 6 weeks. Results showed that artificially bred fish had a higher mean weight gain (2.31 g) and survival rate (48.17%) than those from natural breeding having 2.10 g and 44.26% respectively. The results suggest that artificial breeding using synthetic hormone (Ovaprim) yielded better spawning success and survival rate than natural process. Keywords: Paradise fish, natural breeding, hormone, fertilization, survival