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Fingerling channel catfish (Ictalurus punctatus) were hot branded at 20 and 30 weeks of age (mean weights, 6.7 and 26.5 g, respectively). Of the fish branded at 20 weeks of age, 97% retained readable brands for 20 weeks; of those branded at 30 weeks, 96% retained readable brands for 18 weeks. When the fingerlings of each group were compared with unbranded controls at 54 weeks of age, no significant differences were found in percent survival. At this age, the fingerlings branded at 20 weeks weighed significantly less than did the controls. No difference was found between fingerlings branded at 30 weeks and their controls. Channel catfish reared in warm-water, high-density culture systems should probably be branded no earlier than 30 weeks (or a mean weight of about 27 g). They should be rebranded no later than 16 weeks after the initial branding. 24 c 28 93 29 97 26 93 •' Initial number = 45. h Percent of survivors. "One replication lost; data from 2 replications.

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Data on body weight, five body measurements, dress-out weigbt, and lipid content were collected from 56-week old channel catfish, Ictalurus punctatus, which belonged to 18 full-sib families. Analyses of variance showed that: (1) all sex differences, except that in dressing percentage and lipid content, were significant (P < 0.01); (2) the sex component of variance in percent of total variance ranged from 0.0% for lipid content to 34.7% for interorbital width;(3) all family differences were significant (P < 0.01), while those between replicate tanks were insignificant (P > 0.05); (4) differences between families or individual fish contributed most to total variance while those between tanks and family X tank interactions contributed least; (5) in all characters observed, the family component of variance ranged from 12.6% (dress-out %) to 49.2 % (head length) of total variance. Dress-out weight was positively and highly correlated with body weight, body measurements, or head weight (r= 0.89 or more). The correlations between percent dress-out and these characters were medium or small (r = 0.25-0.54). With the exception of percent head weight, all other characters had medium or small correlations with lipid content (r • 0.15-0.49). Percent head weight was negatively but moderate]y correlated with dress-out weight, dress-out percentage, and lipid content. Knowledge of the sources of variations in different characters and their correlations are valuable aids to workers in fish research

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