Abstract

Evaluation of red monascal rice supplementation on growth, digestive function and oocyte maturation were investigated in Siamese fighting fish (Betta splendens). Completely randomized design with different dietary levels of red monascal rice (0.00, 0.25, 0.50, 1.00 and 2.00%) was conducted for six weeks. The growth of fish fed a control diet was not statistically different (P > 0.05) from a diet containing 0.25% of red monascal rice. However, significantly lower values (P < 0.001) were observed in fish fed more than 0.50% red monascal rice, in a dose-dependent manner. Muscle RNA concentrations were higher in fish fed control diet than in fish fed red monascal rice, while protein concentration and RNA/protein ratio were similar. Body composition and fatty acid profiles (saturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids, total omega-3 and total omega-6) were unchanged among dietary treatments. Digestive functions were perturbed by decreasing the specific activities of amylase, total protease, trypsin and chymotrypsin (P < 0.001), and increasing the specific activity of lipase (P < 0.005). Reproductive consummation of oocytes was significantly different in fish fed red monascal rice, due to increasing RNA concentration and RNA/protein ratio (P < 0.003) and decreasing specific activities of trypsin- and chymotrypsin-like enzymes (P < 0.03). These findings suggest the toxicological effects of red monascal rice by interfering with growth, digestive function and oocyte maturation in Siamese fighting fish.

Key words: Digestive enzyme, fatty acid, growth, muscle, oocyte, red monascal rice, Siamese fighting fish.

Abbreviation

Abbreviations: SGR, Specific growth rate; DSI, digestosomatic index; GSI, gonadosomatic index; MOFA, monounsaturated fatty acid; PUFA, polyunsaturated fatty acid.