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1.
Proliferative gill disease (PGD) is a serious problem in the farm-raised channel catfish Ictalurus punctatus industry. Interrupting the life cycle of the sporozoan causative agent by eliminating Dero digitata worms from culture ponds would be one method of controlling PGD. Eight chemicals—sodium chloride, hydrogen peroxide, formalin, potassium permanganate, liquid copper sulfate, chloramine-T, rotenone and Bayluscide—were tested for acute toxicity against D. digitata . Static, single compound acute toxicity tests were conducted using three replications (10 worm/replicate) of six chemical concentrations and a control. Spearman-Karber analysis was used to calculate 24- and 48-h LC50 concentrations based on active ingredient for each compound. Calculated 24-h LC50 values were: sodium chloride 6,800 mg/L, hydrogen peroxide 13.2 μL/L, formalin 23.3 μL/L, potassium perrnanganate 5.7 mg/L, copper sulfate 7.6 mg/L, chloramine-T 29.5 mg/L, rotenone 0.26 μL/L, and Bayluscide 0.24 mg/L. Formalin and hydrogen peroxide may be options for eliminating D. digitata populations in ponds with fish because their LC50 concentrations were consistent with safe concentrations for fish. Rotenone, Bayluscide, chloramine-T, formalin, and potassium permanganate may be useful as a pond sterilization strategy by treating fingerling ponds prior to stocking fish each year. However, the presence of substrate and organic matter in ponds could impact the efficacy of the chemicals and D. digitata's response to treatment. Treatments should be further evaluated to determine field efficacy, procedures for use, and effects on cost of production.  相似文献   

2.
Marbled rabbitfish, Siganus rivulatus, is an economically valuable herbivorous fish and a potential candidate for warmwater aquaculture. This study was carried out to: (1) assess the effect of various oxygen concentrations on survival and behaviour of S. rivulatus fingerlings and (2) investigate the response of S. rivulatus to hypoxia and determine its critical oxygen tension (Pcrit). In the first experiment, groups of rabbitfish (15 fish per group) were maintained for 1 h in waters of various oxygen concentrations. They were then transferred to well‐aerated tanks and observed for 72 h. Survival was recorded, fish behaviour at low oxygen concentrations observed, and LC50 after 1‐h hypoxia and 72‐h recovery evaluated. In the second experiment, a series of stop‐flow respirometry experiments were performed during which dissolved oxygen was allowed to drop to 0.5 mg L?1 and respiration rate recorded at various oxygen concentrations. In the first experiment, all fish survived for 1 h at oxygen concentration of 1.44 mg L?1 and greater, but started dying at oxygen concentrations below 0.65 mg L?1 (16% survival). The LC50 of S. rivulatus fingerlings was 0.6 mg L?1. Results of the second experiment showed that S. rivulatus is an oxyregulator until Pcrit (1.7 mg L?1 O2) is reached, becoming an oxyconformer below this concentration. Findings allow for a better understanding of environmental oxygen tolerances and minimum acceptable oxygen concentration in rabbitfish aquaculture.  相似文献   

3.
Abstract. Pure cultures of the fungus Haliphthoros philippinensis isolated from infected Penaeus monodon larvae were exposed for 24 h to varying concentrations of the antifungal agents Benlate, calcium hypochlorite, clotrimazole, copper sulphate, Daconil, formalin, Fungitox, Furanace, griseofulvin, hydrogen peroxide, malachite green, Mysteclin C, phenol, potassium permanganate, Resiguard, Tide, tolnaftate and Treflan. The efficiency of each compound in inhibiting sporulation and mycelial growth of the fungus was measured. The results establish mycostatic and mycocidal levels for each fungicide.  相似文献   

4.
The prophylactic use of potassium permanganate (KMnO4) and oxytetracycline and its effects on catfish growth were assessed. For eleven weeks, healthy channel catfish, Ictalurus punctatus, juveniles were exposed to KMnO4 and oxytetracycline. KMnO4‐treated fish were exposed to 1 ppm twice a week for 1 h, while oxytetracycline‐treated fish received a 50 mg/kg dose in the feed (35 fish per tank, two tanks per treatment). Assessed parameters included body weight and length, specific growth rate (SGR), feed intake (FI), condition, and feed conversion index (FCI). Potassium permanganate did not have a suppressive effect on growth, while oxytetracycline significantly enhanced growth on channel catfish (weight and length), as they were heavier (12.5%) than KMnO4‐treated fish and controls at the end of the trial. SGR (%/d), FI, and FCI were not significantly different (P > 0.05) among the three groups of fish. Condition index (K) was significantly higher (ANOVA, P < 0.05) in the oxytetracycline‐treated fish. The present study suggests that, at concentrations commonly used in aquaculture, exposure of healthy channel catfish to oxytetracycline enhanced growth, while KMnO4 does not induce growth suppression.  相似文献   

5.
The efficacies of formalin, potassium permanganate, sodium chloride, and copper sulfate as prophylactic treatments for saprolegniosis (“winter kill”) in channel caffish Icralums puncratus were evaluated. Formalin and copper sulfate were also evaluated as postinfective treatments for the disease. Each of the five experiments was conducted with 5–to 7-g channel catfish placed in static water aquaria maintained in refrigerated tanks. Water temperature was reduced from 25 to 10 C within 36 h and maintained at 10 ± 0.5 C for 28 d. Fish were exposed to cultured Saprolegnia sp. at 20 C, and morbidity and mortality data were recorded for 28 d. Saprolegnia sp.-associated mortalities occurred 7–10 d after exposure. Formalin (25 mg/L) was effective as both a prophylactic and postinfective treatment for saprolegniosis. Copper sulfate was effective in preventing saprolegniosis at a concentration of 0.1 mg/L, but was ineffective as a postinfective treatment. Sodium chloride at 5,000 mg/L was effective in preventing saprolegniosis, but was not practical for use in the commercial catfish industry. Potassium permanganate (up to 0.5 mg/L) was not effective in preventing or treating saprolegniosis in channel caffish. Based on the results of this study, it may be possible to prevent saprolegniosis in channel catfish using formalin or copper sulfate during winter when fish are immunosuppressed by rapid decreases in water temperature or to treat infected fish with formalin. However, the routine use of chemicals to control this disease should not be recommended until studies on their efficacy under typical caffish culture conditions and the effect of long-term use of chemicals on fish and on the environment are completed.  相似文献   

6.
There has been strong interest in the use of peracetic acid (PAA) in aquaculture as it can be used to disinfect water and hard surfaces and thereby eliminate or lower the burden of fish pathogens. Unfortunately, there has been little research on the toxicity of PAA to fish. Twelve species of fingerling fish that are important to aquaculture were exposed to PAA for 24 h in static toxicity bioassays in well water. These fish were: fathead minnow, Pimephales promelas; black‐nose crappie, Pomoxis nigromaculatus; bluegill, Lepomis macrochirus; blue tilapia, Oreochromis aureus; channel catfish, Ictalurus punctatus; golden shiner, Notemigonus crysoleucas; goldfish, Carassius auratus; grass carp, Ctenopharyngodon idella; largemouth bass, Micropterus salmoides; rainbow trout, Oncorhynchus mykiss; sunshine bass, Morone chrysops × M. saxatilis; and walleye, Sander vitreus. Median lethal concentration (LC50) values were estimated with the trimmed Spearman–Karber method using nominal PAA concentrations. The mean 24‐h LC50 values ranged from 2.8 to 9.3 mg/L PAA. Fathead minnow were very sensitive and blue tilapia were very tolerant to PAA exposure; LC50 values of other species tested were within the range of 4.1–6.2 mg/L PAA. More importantly, the 24‐h no‐observed‐effect concentration (NOEC) ranged from 1.9 to 5.8 mg/L PAA; the NOEC would be considered as the safe range for culturists to investigate the use of PAA. Decreased alkalinity/hardness increased the toxicity of PAA, while a small increase of dissolved organic content had no effect on PAA toxicity. Results of the present study are important information on the safe application of PAA for the aquaculture industry.  相似文献   

7.
Ammonia is a metabolite of aquatic organisms which might reach deleterious levels in intensive fish farms. The aim of the present study was to determine median lethal concentrations (96‐h LC50) of total ammonia nitrogen (TA‐N) on marbled spinefoot rabbitfish (Siganus rivulatus) and chronic effects of TA‐N on survival, growth and behaviour of juvenile rabbitfish over a 50 day period. In the first experiment, fish were exposed to 0, 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20 mg L?1 TA‐N for 96 h and survival evaluated. In the second experiment, 12 fish were stocked per 50‐L tank and treated with one of 0, 2, 4, 6, 8, 10 and 12 mg L?1 TA‐N with three replicate tanks per treatment. Survival and growth were determined and histopathological alterations of gills due to chronic ammonia exposure were studied by light and electron microscopy. The 96‐h LC50 values were 16–18 mg L?1 TA‐N. In the chronic exposure experiment, fish reared in water with 0 mg L?1 TA‐N had 100% survival and had 50% weight increase in 50 days. Fish at 2 and 4 mg L?1 TA‐N all died whilst fish in 6, 8, 10 and 12 mg L?1 TA‐N survived and grew albeit less than in treatment 0 mg L?1. Gills from ammonia treated fish displayed severe histological and ultrastructural alterations including hyperplasia, hypertrophy and fusion of secondary lamellae, aneurysms and presence of pleomorphic altered cells. Chronic exposure to ammonia is deleterious to marbled spinefoot rabbitfish and low concentrations of ammonia appear to kill the fish in <50 days whilst fish can survive for more than 50 days at concentrations between 6 and 12 mg L?1 TA‐N.  相似文献   

8.
Abstract. Chinook salmon, Oncorhynchus tshawytscha (Walbaum), and rainbow trout, Salmo gairdneri Richardson, were used to determine if sublethal copper exposure would increase their susceptibility to Vibrio anguillarum infection. Fish were pretreated with copper at fractional levels of the 96 h copper LC50 before exposure to the pathogen. Mortality by vibriosis was greater among fish exposed to 9% of the copper LC50 for 96 h than unexposed fish. Peak susceptibility to vibriosis depended in part on the interaction of exposure time and copper concentration. The higher copper concentrations produced peak susceptibility to infection in shorter time periods. After the peak of susceptibility, sensitivity to infection declined to near control levels in those fish where exposure was continued. Rainbow trout stressed by copper required about 50% fewer pathogens to induce a fatal infection than non-copper exposed fish.  相似文献   

9.
Ichthyophthirius multifiliis (Ich) is a ciliate parasite that infects many species of freshwater fishes worldwide and causes heavy economic losses in aquaculture. Currently, parasiticides for controlling this parasite are limited, and few pond‐practical chemical therapies exist. Hence, the search for new parasiticides is urgently needed. One challenge confronting the screening of potential parasiticides is the difficulty in raising enough parasite for efficacy testing as Ich is an obligate parasite. This study used species of Tetrahymena, Ich‐related and cultivable ciliate protozoa, to evaluate two in vitro methods to test parasiticides. Plate counting and MTS assays (CellTiter 96® AQueous Non‐Radioactive Cell Proliferation Assay) were used to compare lethal concentrations or median lethal concentrations (LC50) of copper sulphate, formalin and malachite green between T. thermophila and Ich theronts or between T. thermophila and Ich tomonts. The parasiticides that killed T. thermophila have been demonstrated to kill theronts or tomonts. These in vitro methods using T. thermophila can be used to screen novel parasiticides against Ich.  相似文献   

10.
Abstract

Copper sulfate is an algicide that is commonly used for phytoplankton and filamentous algae control and has been used as a therapeutant in aquaculture. The objectives of this study were to determine the acute toxicity of copper sulfate and the safe level for use in freshwater prawn, Macrobrachium rosenbergii, production ponds in a high calcium and alkalinity environment. Six concentrations of copper sulfate (0, 0.2, 0.4, 0.6, 0.8, 1.0 mg/L) were tested in 8-L glass aquaria for 48 hours with three replicate aquaria per treatment. Concentrations of calcium hardness and alkalinity were set at 100 mg/L using calcium chloride and sodium bicarbonate, respectively. After 48 hours, survival of the control treatment (0% CuSO4) averaged 97%, which was significantly higher (P< 0.05) than that of all other treatments. The survival in the 0.2 mg/L and 0.4 mg/L (70% and 73%, respectively) concentrations of CuSO4 were significantly greater (P< 0.05) than higher dose treatments; but were not significantly different from each other (P> 0.05). Treatments containing 0.6, 0.8, and 1.0-mg/L copper sulfate demonstrated a dramatic decrease in prawn survival, which averaged 30, 7, and 0%, respectively. Regression analysis of the data predicted 48-hour LC50 for copper sulfate tobe0.46 mg/L. Since recommended application rates for use of copper sulfate as an algicide are 1.0 mg/L or more for water with alkalinities of 100 mg/L, copper sulfate treatments are not recommended for prawn production ponds.  相似文献   

11.
Sea bream, Sparus aurata, is one of the most important fish species that is commonly cultured in the Mediterranean and the eastern coasts of the Atlantic Ocean. The life cycle of sea bream in its natural habitat passes through hyposaline and hypersaline lagoons. It is important to determine the tolerance of the fish to nitrogenous compounds for aquaculture at maximum stocking densities. In the present study, a series of acute experiments were performed to evaluate the effect of salinity on ammonia and nitrite toxicity to sea bream. The fish were exposed to different ammonia and nitrite concentrations according to the static renewal methodology at three different salinities (10, 20, and 30 ppt) and at a temperature of 20 C and a pH of 8.2. The toxic effect of total ammonia nitrogen (TAN) and nitrite nitrogen (NO2‐N) decreased with increasing salinity levels (P < 0.001). Acute toxicity (96‐h lethal concentration 50 [LC50]) values of TAN were determined to be 5.93, 11.72, and 19.38 mg/L at 10, 20, and 30 ppt salinity, respectively. The 96‐h LC50 values of NO2‐N were determined to be 370.80, 619.47, and 806.33 mg/L at 10, 20, and 30 ppt salinity, respectively. Results indicate that sea bream is less tolerant to ammonia but more tolerant to nitrite compared with some other fish species.  相似文献   

12.
Abstract. The sensitivity of Lagenidium spp. isolated from Penaeus monodon and Scylla serrata to 34 antimycotic compounds was determined. Mycostatic effects were evaluated from observations of chemicals on the development of vesicles, zoospores and mycelial growth and on these bases three classes of mycostatic effect were recognized. Zoospores were inhibited by < 1 mg/1 of clotrimazole, crystal violet, econazole nitrate, malachite green, treflan and trifluralin; 1-5 mg/1 of benzalkonium chloride, daconil, domestic detergent, basic fuchsin and furanace; and 10-50 mg/1 benlate, formalin, griseofulvin, phenol and potassium permanganate. Variable mycostatic levels, however, were exhibited with copper sulphate, 2,4-D, hydrogen peroxide, methylene blue, pimaricin, resiguard and tolnaftate while amphotericin, iodine, nystatin, triacetin, boric acid, fungitox and PVP-iodine proved to be poor antifungal agents.  相似文献   

13.
The aim of this study was to evaluate the impacts of different disinfectants' treatment using in aquaculture on the oxidative stress biomarkers such as thiobarbituric acid reactive substrates (TBARS) and carbonyl derivatives of protein oxidative modification, as well as antioxidant defences [superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) and glutathione peroxidase (GPx) activity] and total antioxidant capacity (TAC) in the heart tissue of rainbow trout (Oncorhynchus mykiss). In the disinfectants exposure, fish were treated to chloramine‐T (final concentration 10 g m?3), chloride dioxide (5 g m?3), formalin (200 mL m?3) and CIP disinfectant based on peracetic acid and hydrogen peroxide (16 mL m?3) for 20 min and repeated three times every 3 days. Both chlorine dioxide and formalin treatment was indicated by a significant increase in the level of heart TBARS levels and carbonyl derivatives content and decreased SOD activity. Tissue oxidative stress biomarkers were unchanged upon chloramine‐T or CIP disinfectant exposure. Increased oxidative stress could modify antioxidant defences, principally causing increased CAT activity in the heart tissue of formalin‐ or ClO2?‐exposed fish. The correlation between oxidative stress biomarkers and GPx activity indicates that enzymes related to glutathione metabolism were responsible to formalin or ClO2?‐induced oxidative stress. Hence, TBARS, carbonyl derivatives and antioxidant defences could be used as biomarkers in evaluating the toxicity of formalin and chlorine dioxide using as disinfectants to trout.  相似文献   

14.
闫超  刘璇  张瑞丽  宋志文 《河北渔业》2011,(12):13-16,23
硝化细菌是一种在水产养殖中应用较为普遍的微生态制剂,对于养殖水体水质净化至关重要,养殖系统中消毒剂和抗生素的使用会对硝化细菌活性产生不同程度的影响.本研究选取4种消毒剂(高锰酸钾、硫酸铜、戊二醛和84消毒液)和2种抗生素(土霉素和磺胺),研究不同浓度条件下消毒剂和抗生素对硝化细菌菌剂活性的影响.结果表明,4种消毒剂中高...  相似文献   

15.
Formalin (37–40% formaldehyde) is one of the most effective, widely used chemical in pisciculture for its antiparasitic, antifungal and prophylactic activities. It is used in paints, cleaning products and textile industry, as well. Genotoxic and histological effects of sublethal formalin exposure on Nile tilapia (Oreochromis niloticus) are investigated in this study. The semi‐static acute test was employed. One‐tenth, one‐fifth and half of the 96‐h LC50 value, 148 mg L?1, were used as sublethal exposure concentrations: 15, 30 and 75 mg L?1 for 24, 48, 96 and 168 h respectively. The micronucleus test was applied to investigate the genotoxic effects on fish erythrocytes at the end of predetermined exposure periods and all tissues of the fish were sampled for histological examination. The micronucleus frequencies increased significantly in all exposure groups when compared with their control groups in a dose and time dependent manner (P < 0.05). Results of histological examination showed no histopathological findings in the gonads, heart, skeletal muscle, spleen and intestine tissues after sublethal formalin exposure. Passive hyperaemia of liver tissue in varying proportions, hydropic degeneration, fatty degeneration in high concentrations, branchitis on gill tissues in varying proportions, epithelial lifting, telangiectasia, bleeding in kidney and hyperaemia were found in Nile tilapia exposed to formalin at different concentrations and durations. As a result, it is thought that formalin leads to tissue damage and shows genotoxic effects even at 15 mg L?1 concentration in O. niloticus.  相似文献   

16.
Rabbitfish are an Indo‐Pacific herbivorous marine fish that have good market demand and are suitable for aquaculture. The present work was performed to determine dietary protein inclusion necessary for optimal growth of juvenile rabbitfish Siganus rivulatus. Six diets with increasing levels of protein (10, 20, 30, 40, 50 and 60 g crude protein 100 g?1 feed) and similar levels of gross energy (20 MJ kg?1) were prepared and offered to S. rivulatus juveniles maintained in triplicate cages placed in two large water tanks for 49 days. Growth progressively improved with dietary protein for fish offered diets from 10% to 40% protein inclusion. Diets with greater protein levels did not improve fish growth beyond that observed in the 40% group. Daily feed intake, apparent protein utilization and feed conversion ratio decreased as dietary protein increased. Protein efficiency (PE) was greatest (1.47) in fish offered the 10% protein diet and least in fish offered the 60% protein diet (0.80). No differences in PE were observed among all other treatments (20–50%). Results of the present work suggest that minimum dietary requirement for suitable growth of S. rivulatus juveniles is 40% protein when digestible energy of the diet is 16–18 MJ kg?1.  相似文献   

17.
Lumpfish (Cyclopterus lumpus), a native fish of the North Atlantic Ocean, is utilized as cleaner fish to biocontrol sea lice infestations in Atlantic salmon aquaculture. However, bacterial infections are affecting cleaner fish performance. Vibrio anguillarum, the aetiological agent of vibriosis, is one of the most frequent bacterial infections in lumpfish, and effective vaccine programmes against this pathogen have been identified as a high priority for lumpfish. Vibrogen‐2 is a commercial polyvalent bath vaccine that contains formalin‐inactivated cultures of V. anguillarum serotypes O1 and O2, and Vibrio ordalii. In this study, we evaluated Vibrogen‐2 efficacy in lumpfish against a local isolated V. anguillarum strain. Two groups of 125 lumpfish were bath‐immunized, bath‐boost‐immunized at four weeks post‐primary immunization, and intraperitoneally (i.p.) boost‐immunized at eight weeks post‐primary immunization. The control groups were i.p. mock‐immunized with PBS. Twenty‐seven weeks post‐primary immunization, the fish were i.p. challenged with 10 or 100 times the V. anguillarum J360 LD50 dose. After the challenge, survival was monitored daily, and samples of tissues were collected at ten days post‐challenge. Commercial vaccine Vibrogen‐2 reduced V. anguillarum tissue colonization and delayed mortality but did not confer immune protection to C. lumpus against the V. anguillarum i.p. challenge.  相似文献   

18.
During the summers of 1990 and 1991 in the Lowcountry region of South Carolina, high mortality rates (50-90%) of channel catfish, Ictalurus punctatus, in production ponds were attributed to the toxic form of the blue-green alga (Cyanobacterium) Aphanizomenon flos-aquae. Toxicity varied with algal strain and/or stage in life history, and a simple bioassay was developed to account for the differential toxicity of algae within ponds. The bioassay required an intraperitoneal injection of a sonicated, 30X concentrate of algal cells that are injected into 8- to 20-g fish. Injection with 0.05 ml of concentrate from the toxic strains caused hyperactivity and paralysis in fish within 10 minutes and mortality within an hour. The endotoxin from A. flos-aquae (aphantoxin) was neutralized with the equivalent of 1.7 mg/L potassium permanganate beyond demand. In production ponds, an application of copper sulfate followed with potassium permanganate had variable success. Muddying the ponds had only limited success but appeared promising. Water and soil chemistry in this geographic area probably influenced the frequency of toxic A. flos-aquae blooms.  相似文献   

19.
A decline in the quality of the freshwater fish seed available to small-scale farmers in Asia has been identified as an important constraint on the development of aquaculture in the region. There is a need for simple and reliable methods of determining the quality of seed at the farm gate or hatchery. The present study was carried out, in the field, to develop and evaluate a stress challenge test for Nile tilapia (Oreochromis niloticus, Linn.) fry as the effects of stress on fish performance have been well documented and similar tests are used elsewhere in the sector. Formalin and iodized salt were used as reference toxicants. LC50 values were estimated using mortality figures resulting from exposure of marketable-sized fry to saline and formalin solutions. The two test concentrations, 24 ppt for saline and 500 p.p.m. for formalin, were used as reference toxicants in acute, static bioassays to challenge fry reared under different conditions during the post sex-reversal, nursery period. Using existing farm practice as controls the conditions were: 50% increased stocking density, formalin treatment, 40% reduction in feed rate and no supplementary feed. Fry length proved to be a very significant co-variable; adjusted means showed no significant difference between treatments. The importance of only marketing tilapia fry weighing over 0.2 g was emphasized. It was recommended that the challenge testing approach could be modified, but that it was vulnerable to unquantifiable and uncontrollable factors arising from management and the environment, which may have altered responses to the stressor.  相似文献   

20.
Meagre, Argyrosomus regius, is a candidate marine fish species for aquaculture diversification, presenting a high economic value in the Mediterranean. Tolerance of juvenile meagre to nitrite (NO2‐N) was determined relating to temperature. Fish (3.2 ± 0.6 g and 5.4 ± 0.9 cm) were exposed to different NO2‐N concentrations in a series of acute toxicity tests by the static renewal method at three temperatures (18, 22, and 26 C) at a pH of 8.0. Low temperature clearly increased tolerance to NO2‐N (P < 0.05). The 96‐h median lethal concentration (LC50) values of NO2‐N were 177.63, 139.55, and 49.61 mg/L, at 18, 22, and 26 C, respectively. The safe levels of NO2‐N for juvenile meagre were estimated to be 17.7, 13.9, and 4.9 mg/L at 18, 22, and 26 C, respectively (P < 0.05). This study indicates A. regius is more sensitive to nitrite than other marine fish species cultured in the Mediterranean.  相似文献   

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