The effects of rearing temperature on American glass eels

American eels are declining throughout their range requiring a better understanding of physiological requirements of all life stages and optimal conditions for laboratory rearing and aquaculture. American glass eels (Anguilla rostrata) were housed for 3 weeks at 14d however, there were only marginal differences in final weight between the 18°C and 14°C treatments and no differences in length. Variation in length and weight generally increased as temperature increased with significant differences in the standard error of weight between 14°C and the 22°C and 26°C treatments and between 18°C and 26°C. Mortality was significantly greater than expected by chance at 26°C (7 deaths) and no mortality was observed at 14°C. Body condition (based on the residuals from the weight-length relationships), conversely, was lowest in the 14°C treatment. Considering all response variables, optimal laboratory rearing conditions were observed between 18°C - 22°C. Within a week of experimentation, evidence of gas bubble disease was observed and by completion noted in all treatments except at 14°C, likely as a function of decreased gas solubility at warmer temperatures. Levels of total gas pressure (103% - 108%) and Δp (28 - 54 mm Hg) values may account for the gas bubbles observed.