Assessment of Various Standard Fish Diets on Growth and Fecundity of Platyfish (Xiphophorus maculatus) and Medaka (Oryzias latipes).

Several small freshwater fish species are utilized as models for human conditions and disease in biomedical research. Research animal diets are generally tailored to optimize growth, fecundity, and produce healthy research animals. However, a lack of reference diets presents a barrier in comparative studies between aquatic animal models and even among laboratories using the same species. Therefore, the objective of this study was to determine feeding regime and dietary effects on growth and fecundity in two commonly used freshwater fish, platyfish and medaka. From 1 through 6 months of age, platyfish and medaka were fed one of three feeding regime/diets: (1) our custom feeding regime consists of commercial flake food, beef liver paste, and live brine shrimp (CON); (2) a commercially available zebrafish diet, Gemma (GEM); and (3) a laboratory defined reference feeding regime (WAT). Weight, size, brood numbers, and survival rates for both species were measured monthly. Numbers of platyfish fry and hatch rate of medaka embryos were also determined. We observed that custom feeding regime (CON) fed platyfish and medaka grew larger, exhibited a higher survival rate, and had higher fecundity than WAT or GEM fed fish. These observations suggest that diets and regimes designed for zebrafish are not optimal to maintain platyfish or medaka. Thus, base diets, with clearly defined components and regimes, need to be developed with compositions that can be adjusted in a species-specific manner.