||Gallbladder Color and Relative Fullness as a Field Technique for Estimating Time Since Last Feeding in Brook Trout.
McCormick, J. H. ;
Podoliak, H. A. ;
||Environmental Research Lab.-Duluth, MN. ;Tunison Lab. of Fish Nutrition, Cortland, NY.
Food consumption ;
Food supply ;
Salvelinus fontinalis ;
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Brook trout (Salvelinus fontinalis) fingerlings were held for up to 13 days without food. Gallbladders sampled from these fish at successive times after their last meal showed filling and darkening in color directly related to time since last feeding. It is suggested that these changes may be useful in estimating the feeding state of fish in the field.