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Columnaris disease is an important bacterial disease of commercially grown channel catfish, Ictalurus punctatus. Copper sulphate (CuSO4) 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 CuSO4 is typically included in base diets; a study was conducted to evaluate whether fish feed supplemented with additional CuSO4 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 CuSO4 kg−1 had a mean survival of 22.0% ± 11.0. Fish fed the base plus 80 mg CuSO4 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 CuSO4 kg−1 for 4 weeks had a mean survival of 12.5% ± 6.3. Fish fed the base plus 80 mg CuSO4 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 CuSO4 kg−1 mg not with 40 mg kg−1. [ABSTRACT FROM AUTHOR]

Studies were conducted to determine aspects of water chemistry responsible for large differences in pathogenesis and mortality rates in experimental challenges of channel catfish Ictalurus punctatus with Flavobacterium columnare ; challenges were conducted in water supplying either the Stuttgart National Aquaculture Research Center (SNARC) in Stuttgart, Arkansas, or the Warmwater Aquaculture Research Unit (WARU) in Stoneville, Mississippi. Waters differed in two major characteristics: compared to SNARC water, WARU water contained appreciable dissolved organic matter (DOM) and very low concentrations of dissolved calcium and magnesium. In Experiment 1, fish were exposed to a bacterial challenge of F. columnare in aquaria with either SNARC or WARU water. Fish mortality at 4 d was 100% for fish in SNARC water, while no fish died in WARU water. Bacterial adhesion to gill surfaces also differed dramatically in the two waters and was approximately 1900-times higher for fish challenged in SNARC water (more than 800,000 bacterial CFUs/ng extracted DNA) than for fish challenged in WARU water (fewer than 450 CFUs/ng). Experiment 2 was conducted with a lower bacterial challenge to determine which factor, DOM or divalent cation concentration, caused the difference in mortality seen in Experiment 1. Complete removal of DOM from WARU water by carbon filtration did not affect bacterial adhesion to gills nor resulted in greater mortality in challenged fish. Consequently, DOM did not contribute to the differences in mortality seen in Experiment 1. However, removal of most calcium and magnesium from SNARC water by ion-exchange filtration resulted in decreased bacterial adhesion to gill and decreased mortality compared to un-altered SNARC water. It appears that the concentration of divalent cations (hardness) affects the pathogenesis of columnaris disease. [ABSTRACT FROM AUTHOR]

A study was conducted to compare the effects of two chemical therapeutants on channel catfish (CCF)Ictalurus punctatusconcurrently infected withFlavobacterium columnareandIchthyobodo necator. Copper sulfate (CuSO4) and potassium permanganate (KMnO4) were investigated for their ability to reduce the bacterial load, parasite load, and subsequent mortality.Treatment rates of CuSO4or KMnO4were 2.1 mg/L and 3.0 mg/L, respectively, and were applied at 24 h intervals on three consecutive days and control fish were untreated. Fin and gill samples were taken on day 4 (24 h after the final treatment) and day 10 (one week after the final treatment) for quantification of parasite and bacterial load. The survival rate of CuSO4-treated fish (73.0 %) was significantly different from the untreated control fish (41.5%). KMnO4-treated fish was (53.6%) and not significantly different from untreated control or CuSO4-treated fish.I. necatorloads were significantly reduced by both CuSO4and KMnO4,but only CuSO4significantly reduced theF. columnareload. [ABSTRACT FROM PUBLISHER]

Columnaris disease is one of the most important bacterial diseases affecting Channel Catfish Ictalurus punctatus commercially grown in the USA. This disease can greatly diminish the profitability of aquaculture operations by large-scale mortality events, particularly in the fingerling production phase. Three experiments were conducted to evaluate the susceptibility of Channel Catfish fingerlings to columnaris disease when they were preexposed to copper sulfate (CuSO4). In experiment 1, fish were exposed for 24 h to 0, 1, 2, or 4 mg/L CuSO4 and were challenged immediately with Flavobacterium columnare, the etiological agent of columnaris disease. The resulting survival data indicated that fish preexposed to CuSO4 and then challenged exhibited significantly lower survival than did fish not exposed and then challenged. Experiment 2 was designed as above, except after the 24-h static exposure to CuSO4, fish were subjected to an additional 24 h in flow-through water prior to the challenge with F. columnare. In contrast to experiment 1, fish preexposed to CuSO4 and allowed an additional 24 h in flow-through water had a significantly higher survival rate than fish not exposed and then challenged. Experiment 3 evaluated the longevity of resistance to columnaris disease afforded by preexposure to CuSO4; in this experiment the remaining fish from experiment 2 were challenged 9 d after exposure to CuSO4. The increased survival rate of fish preexposed to CuSO4 was still significantly different, indicating the incurred resistance to F. columnare lasts for at least a week after exposure to CuSO4. [ABSTRACT FROM PUBLISHER]