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The effect of diet on dorsal fin erosion in steelhead trout (Oncorhynchus mykiss)

William A. Lellis·Frederic T. Barrows
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Abstract

A 2 × 2 factorial experiment of diet type (krill vs. fish meal) and steroid supplementation (0 vs. 30 μg 17α-methyltestosterone kg − ) was conducted to determine the effects on dorsal fin erosion in steelhead trout. Triplicate tanks of 250 fry were fed one of the four diets at a rate calculated to produce 115 g fish in 34 weeks. Fish were transferred to larger tanks when mean density index reached 0.40. Dorsal fin index (DFI, measured as mean dorsal fin height × 100/total fish length) was greater ( P < 0.001) among fish fed krill-based diets than for fish fed fish-based diets at weeks 12, 22, and 34 of the trial. Added testosterone decreased ( P = 0.04) DPI among fish fed the krill diet at week 12 but otherwise had no effect on fin condition. Addition of testosterone to either diet type decreased ( P = 0.02) critical thermal maximum, which is a measure of fish resistance to thermal stress. The results suggest that diet composition can influence the rate of dorsal fin erosion in steelhead trout through a metabolic, behavioral, or combined change.

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William A. Lellis, Frederic T. Barrows. 1997. The effect of diet on dorsal fin erosion in steelhead trout (Oncorhynchus mykiss). https://doi.org/10.1016/s0044-8486(97)00133-6

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