Billy R. Griffin

Efficacy of Copper Sulfate for the Treatment of Ichthyophthiriasis in Channel Catfish

Abstract Ichthyophthirius multifiliis is a protozoan that may infest and significantly damage cultured fish species. The purpose of this study was to measure the efficacy of copper sulfate in treating ichthyophthiriasis. Fingerling channel catfish Ictalurus punctatus exposed to at least 2,000 theronts of I. multifiliis per liter of water developed consistent infestations of I. multifiliis (20 or more trophonts on the dorsal surface of the head of the fish). Infestation was observed in untreated controls at day 5 after exposure and mortality occurred after day 10. Coexposure studies with theronts and different concentrations of copper sulfate revealed that all theronts were killed at concentrations greater than 0.05 mg/L. To determine the effect of copper sulfate in the treatment of ichthyophthiriasis, fish were exposed to the parasite until trophonts were observed (day 5), and they were subsequently treated with copper sulfate. The lowest effective concentration of copper sulfate for treatment of ichthyop...

Relationship between expression of hepatic metallothionein and sublethal stress in channel catfish following acute exposure to copper sulphate

Abstract Copper sulphate is frequently used as a general biocide in the aquacultural industry. The acute effects of copper sulphate on sublethal endpoints of stress and tissue damage in channel catfish have not been explored previously. Consequently, the purpose of this study was to examine the effects of a therapeutically relevant dose of copper sulphate on plasma cortisol, hepatic metallothionein (MT) expression, hepatic copper content and plasma concentrations of aspartate aminotransferase (AST). Exposure of prespawn juvenile catfish to 1.7 mg/l as copper sulphate (326±9.4 μg/l copper; 175–180 mg/l CaCO 3 ; pH 7.45) led to time-dependent increases in hepatic MT expression, hepatic copper content as well as plasma cortisol concentrations. Exposure to a 1 h confinement stress led to a redistribution of copper to the liver but no significant increases in hepatic MT or plasma cortisol after 23 h. Neither stress nor copper exposure caused liver damage as measured by AST. The parallel expression of hepatic MT with plasma cortisol and hepatic copper residues suggests that MT may serve as a useful indicator of acute stress and acute exposure to copper sulphate in channel catfish.

Sexual differences in mortality and sublethal stress in channel catfish following a 10 week exposure to copper sulfate

Abstract Copper sulfate is regularly used in the aquaculture industry as an algicide and for the treatment of various ectoparasitic infections. In this study, male and female channel catfish ( Ictalurus punctatus ) (100 fish per group) were treated for 10 weeks with three levels of copper sulfate, giving water concentrations of 220, 354, and 465 μg Cu 1 −1 . Six fish were sampled at 2-week intervals and copper levels in muscle and hepatic tissue were measured. No copper accumulation was detected in muscle tissue during the exposure period, but hepatic accumulation began to occur within the first 2 weeks of treatment, with a peak at 4–6 weeks and subsequent decrease before the end of exposure. No mortality was seen in controls or at 220 mg Cu 1 −1 . However, lethality was seen within the first week in the 354 and 465 μg Cu 1 −1 exposures, with males being more susceptible than females. Metallothionein (MT) levels showed an increasing trend through the 6-week time point, followed by a general decrease toward control levels for the remainder of the exposure. The pattern of hepatic MT content was similar to that of hepatic copper accumulation, with a correlation coefficient ( r ) of 0.767 ( P ≤ 0.001). Measures of whole-body weight, body length, liver weight, liver somatic index, and condition factor were recorded as indicators of sublethal stress. No substantial change was seen in any of these measures in females; however, a decreasing tendency was seen in males for body weight, body length, and condition factor. However, correlation analysis of hepatic copper with somatic measures showed a significant relationships in both sexes. When hepatic MT was compared to somatic indices, significant correlations were observed in males, but not females. The results of this study indicate an association between MT expression and sublethal stress in males as well as a potential protective mechanism other than MT in prespawn female channel catfish exposed to copper.

Efficacy of Potassium Permanganate in Treating Ichthyophthiriasis in Channel Catfish

Abstract Epizootics of ichthyophthiriasis can be controlled with potassium permanganate (KMnO4), but its effectiveness has not been confirmed by controlled studies. The purpose of this study was to determine the concentration of KMnO4 needed to halt an active Ichthyophthirius multifiliis infestation in channel catfish Ictalurus punctatus. Juvenile channel catfish were exposed to fish infested with I. multifiliis until they developed immature trophonts. They were then moved to individual static containers with 2 L of filtered well water, where they were treated with KMnO4 daily for 10 d. The lowest effective dose of KMnO4 required to eliminate theronts was 1.25 mg/L. The results indicate that KMnO4 is effective for controlling I. multifiliis epizootics at low concentrations in clean water. However, effective treatment in ponds will be strongly influenced by detoxication of KMnO4 depending on the concentration of easily oxidizable substances in the water.

Prevention of an Initial Infestation of Ichthyophthirius multifiliis in Channel Catfish and Blue Tilapia by Potassium Permanganate Treatment

Abstract Potassium permanganate (KMnO4) has been used to control infestations of Ichthyophthirius multifiliis, but its effectiveness has not been reported from controlled efficacy studies. The purpose of this study was to determine the acute toxicity of KMnO4 to the I. multifiliis theront and the concentration needed to prevent an initial infestation of I. multifiliis in juvenile channel catfish Ictalurus punctatus and blue tilapia Tilapia aurea. Ichthyophthirius multifiliis theronts were exposed to concentrations of KMnO4 in 100 μL of well water in 96-well plates and observed for 4 h to determine the acute toxicity. A concentration of 0.9 mg KMnO4/L caused greater than 95% mortality of the theronts in 4 h in well water; the 4-h LC50 (concentration lethal to 50% of test animals) value was estimated to be 0.77 mg/L. Juvenile channel catfish were exposed to 10,000 theronts/L of well water and immediately treated with a single dose of KMnO4. Infestation occurred in controls 6 d after exposure. The lowest eff...

Histological and Hematological Evaluation of Potassium Permanganate Exposure in Channel Catfish

Abstract A histological and hematological study was performed to evaluate the effect of waterborne exposures of channel catfish Ictalurus punctatus to potassium permanganate (KMnO4). Three concentrations of KMnO4 were chosen to represent one, three, and five times the therapeutic concentrations (0.438, 1.315, and 2.190 mg/L, respectively), based on the KMnO4 demand, for 36 h, which is three times the usual treatment duration. The organs examined were the gill, liver, and trunk kidney. Differential leukocyte counts of neutrophils and monocytes in the blood and plasma enzyme analyses (lactate dehydrogenase and alanine transaminase) were also performed. The gill was the only organ to show microscopic lesions. Fish exposed to the therapeutic concentration of KMnO4 for 36 h had mild hypertrophy and spongiosis in the gills sampled during exposure, but no lesions were noticed 2 d postexposure. Gills of fish exposed to three and five times the therapeutic dose had extensive hyperplasia, epithelial hypertrophy and...

Effect of Simulated Copper Sulfate Therapy on Stress Indicators in Channel Catfish

Abstract Plasma cortisol concentrations in juvenile channel catfish Ictalurus punctatus exposed to 1.7 mg copper sulfate/L for 24 h in a simulated therapeutic treatment episode rose to a level significantly greater than unexposed fish and declined when the exposure was discontinued. Plasma glucose concentrations were elevated immediately and increased during exposure to twice the level in control fish. The maximum glucose concentration was followed by a slow decline to the preexposure level by 54 h after discontinuing exposure. Plasma lactate concentrations did not change until after the exposure period, but by 30 h there was a significant increase. Plasma chloride levels were significantly reduced during exposure and remained so before returning to preexposure levels by 54 h after exposure. No changes were observed in hematocrit values, hepatic metallothionein protein, or in plasma-associated aspartate aminotransferase, alanine aminotransferase, and lactic dehydrogenase, suggesting that little cellular d...

Comparative acute toxicity of potassium permanganate to nontarget aquatic organisms

Potassium permanganate (KMnO4) is used worldwide in freshwater pond aquaculture for treatment and prevention of waterborne external parasitic, bacterial, and fungal diseases. Nevertheless, KMnO4 has not been approved by the U.S. Food and Drug Administration, and insufficient information exists to allow evaluation of the environmental risk of KMnO4 exposures. Limited data exist concerning KMnO4 toxicity to nontarget species in systems receiving aquaculture effluent from treated ponds. The goal of this research is to generate effects data for use in developing an ecological risk assessment of KMnO4. Toxicity tests were used to compare the relative sensitivities of five standard aquatic test species to KMnO4. Acute toxicity test results using synthetic moderately hard water show static 96-h mean median lethal concentration (LC50) values +/- standard deviation (SD) of 0.058 +/- 0.006 mg/L for Ceriodaphnia dubia, 0.053 +/- 0.009 mg/L for Daphnia magna, 2.13 +/- 0.07 mg/L for Pimephales promelas, 4.74 +/- 1.05 mg/L for Hyalella azteca, and 4.43 +/- 0.79 mg/L for Chironomus tentans. Most of these values are below the recommended KMnO4 treatment rate of at least 2.0 mg/L or 2.5 times the waters potassium permanganate demand (PPD; an estimation of the available reducing agents in the exposure water), suggesting significant environmental risk. However, repeating these laboratory tests using pond water resulted in significantly reduced toxicity, with static 96-h mean LC50 values (+/-SD) of 2.39 +/- 0.36 mg/L for C. dubia, 1.98 +/- 0.12 mg/L for D. magna, 11.22 +/- 1.07 mg/L for P. promelas, 13.55 +/- 2.24 mg/L for H. azteca, and 12.30 +/- 2.83 mg/L for C. tentans. The PPD of synthetic moderately hard water was 0.329 +/- 0.114 mg/L; however, pond water PPD was 5.357 +/- 0.967 mg/L. The effective disease-treating dose based on 2.5 times the PPD would thus be 0.823 and 13.392 mg KMnO4/L, respectively, exceeding the LC50 for most of these nontarget organisms, even in pond water, immediately after treatment.

Histologic Evaluation of the Safety of Copper Sulfate to Channel Catfish

Abstract A histological study was done to evaluate the effect of waterborne exposures of copper sulfate (CuSO4) on channel catfish Ictalurus punctatus. Channel catfish were exposed daily for 11 consecutive days to three concentrations of CuSO4 representing one, three, and five times the recommended therapeutic level based on the total alkalinity. Fish were treated with CuSO4 in water flow-through tanks at a flow rate of 0.633 L/min. More than half the Cu was flushed in 1 h, which is similar to the elimination rates in ponds (due to the rapid uptake of Cu by aquatic plants or algae and the binding to organic and inorganic material). All fish were clinically normal and no fish died during the experiment. All examined tissues were grossly and histologically normal as well. The absence of histological lesions was attributed to the brief daily exposure to copper and to moderate total alkalinity and total hardness of the well water used. The results of this study suggest that CuSO4 is safe for channel catfish p...

Effect of Waterborne Potassium Permanganate Exposure on Manganese Content in Liver and Axial Muscle of Channel Catfish

Abstract Adult channel catfish Ictalurus punctatus were exposed to waterborne potassium permanganate for 12 weeks to determine if such exposure would alter the manganese content of axial muscle or liver tissue. Continuous exposure to 0.5 mg KMnO4/L or exposure to 1 or 2 mg KMnO4/L on alternate days did not cause a significant increase in manganese in axial muscle or liver tissue. The mean (±SE) concentration of manganese in axial muscle of unexposed controls was 0.262 ± 0.018 mg/kg (wet weight). Means of manganese concentrations in axial muscle of the three exposure groups during the 12 weeks of exposure were 0.289 ± 0.021 mg/kg, 0.269 ± 0.018 mg/kg, and 0.239 ± 0.013 mg/kg for 0.5 (continuous), 1, or 2 mg/L (alternate days), respectively. At specific sampling times there were differences between controls and exposure groups; however, no trend toward higher or lower manganese concentrations in muscle could be detected within groups. The mean (±SE) concentration of manganese in liver tissue of controls was...