MEPS 372:243-252 (2008)  -  DOI: https://doi.org/10.3354/meps07704

ABSTRACT: We measured dry weight and nucleic acid (RNA/DNA) contents of larvae and juveniles of the anadromous river pufferfish Takifugu obscurus for 2 aquaculture salinity series in order to evaluate the effect of different rates of salinity change on fish growth and to determine appropriate rearing conditions for one of the most valuable aquaculture species. In addition, the effect of salinity during starvation was evaluated for 3 stages of development (larvae, juveniles and young fish). Analyses were performed at 1 to 2 d intervals over a period of 1 to 60 d after hatching (DAH). Differences in growth rates of the 2 groups were observed from 36 DAH until the end of the experiment. Specifically, the group in which salinity was increased by 1 ± 0.5 psu d^–1 grew faster than the group in which salinity was increased by 3 ± 0.5 psu d^–1. Significant differences in RNA/DNA ratios between both groups occurred from 30 DAH, with juvenile fish of the 1 psu d^–1 group showing a higher ratio. Under starving conditions, the RNA content per individual decreased against a roughly constant DNA content. Significant differences in the RNA/DNA ratios were found between fed and starved larvae and juvenile fish. Consequently, we verified that RNA/DNA ratios could be used as an index of nutritional condition with respect to the effects of salinity change and recommend that maintaining stable salinity would be helpful in the aquaculture of anadromous river pufferfish.

KEY WORDS: Growth · Nutrition · Pufferfish · RNA/DNA ratio · Starvation · Salinity · Takifugu obscurus