Optimal aquarium shape for rearing male Siamese fighting fish (Betta splendens)

The aggressive behavior of male Siamese fighting fish (Betta splendens) necessitates their rearing in isolation in small aquaria. For intensive production, the major concerns are growth promotion and feed utilization. The small aquaria are connected to save space but little is known about the suitable characteristics of aquaria for this species. In this study, solid-red male Siamese fighting fish (0.57-0.58 g body weight) were individually housed in aquaria that had square (SQ), rectangular (RE), equilateral triangular (ET), or right triangular (RT) cross sections. The water in the aquaria had the same depth (6 cm) and volume (180 mL). At the end of the eight-week trial, fish housed in the ET and RT aquaria exhibited superior growth rate and feed utilization to fish housed in SQ or RE aquaria (P < 0.05). No differences in morphometrics, skin coloration, muscle quality, and whole-body composition were observed. Protein- and lipid-digesting enzyme activities, as well as amylase/trypsin ratios, indicated differences in feed utilization that were correlated with aquarium shape. The findings of our study indicated that the triangular aquaria were more suitable for rearing this fish in isolation. This study could be used as an animal protocol for experimental set-up, to improve betta fish farm management, and also for the development of intensive farming systems for this species.