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Four treatment groups that received repeating cycles of fixed feed deprivation for either 0, 1, 2, or 3 d (control, treatment 1, treatment 2, and treatment 3, respectively), followed by periods of refeeding with a 36% protein commercial catfish feed once daily as long as the active phase of compensatory growth (CG) persisted, were assessed in flow‐through aquaria. No‐feed periods elicited the CG state and were immediately followed by days of ad libatum refeeding. At the end of 10 wk, average growth rate (AGR) of fish was higher (P < 0.05) than the control by 40%, 180%, and 191% for treatment 1, treatment 2, and treatment 3, respectively. The average weight of fish in treatment 3 was heavier (P < 0.05) than the average control group at the end of the study period. Mean daily feed consumption was 3.91%, 5.03%, 5.36%, and 5.98% for control, treatment 1, treatment 2, and treatment 3, respectively. Mean feed consumption per fish per day was 24%, 71.3%, and 70.7% higher than the control in treatment 1, treatment 2, and treatment 3, respectively. Restricted feeding is one of the effective methods to contain ESC‐related losses in commercial channel catfish fingerling operations. The mean cumulative survival of treatment groups registered higher (P < 0.05) survival to Edwardsiella ictaluri infection compared to the daily fed control fish. Results from this study show that compensatory growth response triggered by periodic non‐feeding days can improve growth rate, feed consumption, and improved survival to ESC infections in channel catfish fingerlings.

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Mature channel catfish Ictalurus punctatus were exposed to water containing three different concentrations (20, 40, and 60 mg/L) of AQUI‐S (50% isoeugenol) during routine handling procedures at a commercial catfish facility. Anesthetic efficacy, recovery time, and the effects of AQUI‐S on routine measures of stress were compared with similar measures in a group of fish sampled prior to anesthesia (preanesthesia [PA] group) and a group anesthetized with 100 mg tricaine methanesulfonate (TMS)/L. On average, all the fish lost equilibrium at 8.0, 3.9, and 3.7 min when anesthetized in 20, 40, and 60 mg AQUI‐S/L, respectively. Fish anesthetized with TMS lost equilibrium at 4.5 min. Recovery time in freshwater was 2.1, 2.8, and 5.3 min for fish anesthetized in 20, 40, and 60 mg/L AQUI‐S, respectively. Recovery time after TMS anesthesia was 1.7 min. Short‐term (24‐h) survival was 100% for all treatments, and long‐term (21‐d) survival ranged from 87.5% for TMS‐anesthetized fish to 98.8% for fish anesthetized in 40 mg/L AQUI‐S. All anesthetic treatments significantly reduced (P < 0.05) plasma cortisol levels relative to PA fish, and circulating cortisol was lower (P < 0.05) in all AQUI‐S−anesthetized fish than in TMS‐anesthetized fish. Plasma glucose concentrations were significantly lower (P < 0.05) in fish anesthetized with 40 mg/L AQUI‐S than in PA and TMS‐treated fish after both anesthetization and recovery. Plasma lactate and chloride concentrations were not reduced (P > 0.05) in any treatment compared with the levels in PA fish. Fish anesthetized with 40 mg/L AQUI‐S had lower (P < 0.05) plasma lactate levels after recovery than TMS‐anesthetized fish, and plasma chloride levels were significantly lower (P < 0.05) immediately following AQUI‐S anesthesia at all concentrations than in fish anesthetized with TMS. Anesthesia did not affect (P > 0.05) postrecovery plasma chloride concentrations. Overall, AQUI‐S exhibited efficacy as an anesthetic for mature channel catfish and demonstrated stress‐reducing properties during handling procedures.

Formalin is currently the only aquaculture drug approved by the U.S. Food and Drug Administration for the control of fungi on the eggs of all finfish. The efficacy of formalin for disinfecting hybrid catfish (channel catfish Ictalurus punctatus × blue catfish I. furcatus) eggs was examined and compared with that of three other potential chemotherapeutants. Two experiments were conducted to evaluate treatment dose and frequency on the hatching success of the hybrid catfish. In the first experiment, hybrid catfish egg masses were divided and assigned to 1 of 13 treatments administered as daily 15‐min baths. The treatments were as follows: (1) control (no treatment), (2) 50 ppm (mg/L) formalin (F), (3) 100 ppm F, (4) 200 ppm F, (5) 125 ppm hydrogen peroxide (HP), (6) 250 ppm HP, (7) 500 ppm HP, (8) 50 ppm povidone iodine (PI), (9) 100 ppm PI, (10) 200 ppm PI, (11) 2.5 ppm copper sulfate (CS), (12) 5 ppm CS, and (13) 10 ppm CS. Hatching success tended to be highest among eggs treated with 100 ppm F (87.7%), 2.5 ppm CS (87.0%), or 100 ppm PI (85.2%), although these success rates were not significantly (P > 0.05) different from that in the control treatment (82.8%). Treatment with 500 ppm HP resulted in a significant (P < 0.05) decrease in hatching success (31.5%). In the second experiment, the optimal frequency of formalin treatments was assessed by treating hybrid catfish eggs zero, two, three, or four times daily. Eggs treated three times daily with 100 ppm F had the highest (P < 0.05) percentage of hatched eggs. To maximize hatching success, three daily treatments of hybrid catfish eggs with 100 ppm F as a 15‐min bath is recommended.