Dietary copper effects survival of channel catfish challenged with Flavobacterium columnare

Columnaris disease is an important bacterial disease of commercially grown channel catfish, Ictalurus punctatus . Copper sulphate (CuSO 4 ) has been shown to be therapeutic and prophylactic as a water treatment for columnaris disease. Copper is an essential dietary component in animal feeds and CuSO 4 is typically included in base diets; a study was conducted to evaluate whether fish feed supplemented with additional CuSO 4 at 0, 40 and 80 mg kg −1 of diet and fed at a daily rate of 3% body weight would affect survival to columnaris disease. Results indicate fish fed the copper‐supplemented diet for 2 weeks significantly increased survival following F. columnare challenge. This increase appeared to be dose‐dependent. The mean per cent survival (±SEM) for fish fed the base diet (unsupplemented) for 2 weeks and then challenged was 2.0% ± 1.1. Fish fed the base plus 40 mg CuSO 4  kg −1 had a mean survival of 22.0% ± 11.0. Fish fed the base plus 80 mg CuSO 4  kg −1 had a mean survival of 29.3% ± 13.4. The mean per cent survival for fish fed the base diet for 4 weeks and then challenged was 28.3% ± 9.0. Fish fed the base plus 40 mg CuSO 4  kg −1 for 4 weeks had a mean survival of 12.5% ± 6.3. Fish fed the base plus 80 mg CuSO 4  kg −1 for 4 weeks had a mean survival of 40.5% ± 8.1. There was a significant effect after 4 weeks with fish fed the base plus 80 mg CuSO 4  kg −1 mg not with 40 mg kg −1 .