Growth patterns and feeding characteristics in early developmental stages of Takifugu rubripes cultured in a recirculating aquaculture system

Abstract

The growth patterns and feeding characteristics of Takifugu rubripes at different developmental stages (0–50 days after hatching, DAH) were investigated under artificial breeding conditions using ecological and traditional biological methods. The results revealed rapid growth in head length, head height, and eye diameter from hatching to 50 DAH, and the inflection point for body length growth occurred at 27 DAH. From 27 to 50 DAH, the growth rate slowed. In the swimming organs, the inflection points for tail, pectoral, dorsal, and anal fin growth occurred from 29 to 31 DAH. The growth rate for fins slowed after this period, suggesting the preferential development of important organs related to sensation, locomotion, and feeding during early development, with varied developmental periods. An investigation of the feeding rhythm of T. rubripes larvae, juveniles, and young fish showed that feeding activities mainly occurred during the daytime, a behavior typical of daytime feeders. The average daily feeding rate of T. rubripes was 12.61% for the early-stage larvae at 6 DAH, 43.89% for the late-stage larvae at 15 DAH, 40.05% for juveniles at 30 DAH, and 28.46% for young fish at 46 DAH. In addition, the satiation time for juveniles tended to decrease with increasing age, whereas the time for digestion tended to increase. These data can be used as a reference for the daily feeding of T. rubripes at different developmental stages. Comprehensive understanding of the growth and feeding characteristics of early-stage T. rubripes developed in this study will be useful for the management of artificially bred fry and will aid in promoting the growth and survival rates of aquaculture fish larvae.