| Abstrakt: |
Throughout the growing season, from March to October, marked fish usually made a daily trip to the feeding station. In the spring, they did not use the demand feeders until temperatures reached 12 C and they stopped demand feeding in the fall at approximately 22 C. In the spring, intermittent feeding appeared to be primarily temperature related. At cold temperatures fish did not feed daily. After the water had warmed to 22 C fish fed on a daily basis. During summer, low oxygen concentrations often caused fish to adjust or miss their daily feeding period. Feeding was reduced at oxygen values below 5 mg/liter, but fish occasionally fed at values as low as 3 mg/liter. Large fish were dominant in feeding and small fish usually had to wait. A daily feeding pattern for each size fish was established, and since each fish fed approximately the same time day after day it became acclimated to the prevailing oxygen and temperature values. Interruptions of this feeding routine were observed when oxygen or temperature values fell below those values at which the fish was accustomed to feeding. This could affect all or part of the hierarchical spectrum. Hence, environmental isolation, heretofore undescribed in catfish culture ponds, can operate to reduce the effect of a hierarchy. |
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