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1.
Antifungal agents are essential for the maintenance of healthy stocks of fish and their eggs in intensive aquaculture operations. In the USA, formalin is the only fungicide approved for use in fish culture. However, hydrogen peroxide and sodium chloride have been granted low regulatory priority drug status by the United States Food and Drug Administration (FDA) and their use is allowed. We evaluated the efficacy of these fungicides for controlling fungal infections on rainbow trout eggs. A pilot study was conducted to determine the minimum water flow rate required to administer test chemicals accurately in Heath incubators. A minimum water flow rate of 7.6 1 min−1 was necessary to maintain treatment concentrations during flow-through chemical exposures. The antifungal activity of formalin, hydrogen peroxide, and sodium chloride was evaluated by treating uninfected and 10% fungal-infected (Saprolegnia parasitica) rainbow trout eggs (Oncorhynchus mykiss) for 15 min every other day until hatch. There were no significant differences among treatments in percent hatch or final infection for uninfected eggs receiving prophylactic chemical treatments. Eggs of the negative control group (uninfected and untreated) had a mean hatch exceeding 86%. All chemical treatments conducted on the infected egg groups controlled the spread of fungus and improved hatching success compared with the positive control groups (infected and untreated). Formalin treatments of 1000 and 1500 μl l−1 and hydrogen peroxide treatments of 500 and 1000 μl l−1 were the most effective. Sodium chloride treatments of 30 000 mg l−1 improved fry hatch, but the compound was less effective at inhibiting fungal growths compared with hydrogen peroxide and formalin treatments.  相似文献   

2.
Fungal infestation by water mold Saprolegnia spp. causes great losses in aquaculture and fish egg hatching. To find a safe and effective alternative for the fungal prevention, we studied continuous disinfection of the inlet water by UV irradiation and ozonation combined with low concentration hydrogen peroxide (H2O2) treatments in a rainbow trout (Oncorhynchus mykiss) egg hatching system. High dose of UV irradiation (400 mWs/cm2) of the inlet water decreased the mortality of rainbow trout eggs from the 77.3% to 14.3% in a 28 day trial. UV irradiation did not modify water quality parameters, while combination of UV irradiation and H2O2 caused up to fivefold increase in the formate levels, and combination of O3 and H2O2 caused even ten-fold increase in the acetate and formate levels. UV suppressed the gradual increase of the heterotrophic bacterial counts on the fish eggs. Based on the molecular profiling high dose of UV reduced the growth of some of the dominating bacterial groups and combination of UV and H2O2 had a distinctive effect on the overall bacterial community structure on the fish eggs.  相似文献   

3.
Egg disinfection is considered the most important routine work in hatcheries to avoid fungal and/or bacterial infection of fish eggs. The aim of this study was to determine the effectiveness of three disinfectants: formalin, iodine and sodium chloride on the hatching success of yellow perch eggs. The disinfectants were tested in triplicate at different concentrations for 15 and 30 min bath treatments. Two experiments were conducted; formalin at five concentrations (25, 50, 100, 150 and 200 mg L?1) and 25 mg L?1 iodine were tested in the first experiment. The second experiment involved formalin at three concentrations (250, 500 and 1000 mg L?1), iodine at three concentrations (50, 100 and 250 mg L?1) and sodium chloride at three concentrations (500, 1000 and 3000 mg L?1) were used. Iodine and sodium chloride‐treated eggs hatched earlier than formalin‐treated eggs. The highest mean percentage of eyed stage, hatching rate and survival to first feeding fry was observed at 200 mg L?1 formalin for 30 min, 50 mg L?1 iodine for 15 min and 500 mg L?1 sodium chloride for 30 min. High concentrations of formalin (1000 mg L?1), iodine (250 mg L?1) and sodium chloride (1000 and 3000 mg L?1) showed toxicity to yellow perch eggs, resulting in low hatching rate and survival to first feeding fry. We recommended formalin at a concentration of 150–200 mg L?1 for 30 min as an effective, easily available and low‐cost disinfectant for routine use to improve yellow perch hatchability.  相似文献   

4.
Myxozoan parasites are known pathogens of cultured finfish. Kudoa neurophila n. comb. (Grossel, Dyková, Handlinger & Munday) has historically infected hatchery‐produced striped trumpeter, Latris lineata (Forster in Bloch and Schneider), a candidate species for seacage aquaculture in Australia. We examined the efficacy of four water treatment methods to prevent K. neurophila infection in post‐larval (paperfish) and juvenile striped trumpeter. Treatments included dose‐controlled ultraviolet irradiation [hydro‐optic disinfection (HOD)], ozone with conventional UV (ozone), mechanical filtration at 25 μm and then foam fractionation (primary filtration), and 50‐μm‐filtered sea water (control). In post‐larvae (initially 10.3 ± 2.7 g, mean ± SD, 259 days post‐hatching, dph), the infection prevalence (PCR test) after 51 days was 93 ± 12% in the control, 100 ± 0% in primary filtration and 0 ± 0% in both ozone and HOD. Likewise, in juveniles (initially 114 ± 18 g, 428 dph), prevalence was 100 ± 0% in the control and primary filtration treatments with no infection detected in ozone and HOD. Concurrently, there was a 50–100% reduction in heterotrophic bacteria and 100% reduction in presumptive Vibrio sp. in sea water HOD and ozone treatments. HOD with a dose of ≥44 mJ cm?2 UV was as effective as ozonation at >700 mV ORP for 10 min, in preventing K. neurophila infection.  相似文献   

5.
Surface disinfection trials were performed on eggs from three marine finfish species: California yellowtail (CYT; Seriola lalandi), white seabass (WSB; Atractoscion nobilis) and California halibut (HA; Paralichthys californicus). All three species were spawned from captive populations maintained at the Hubbs‐SeaWorld Research Institute (HSWRI). Five disinfection treatments were used for each species; Treatment 1 included 100 mg L?1 of formalin (F100) for 60 min (current HSWRI treatment), Treatment 2 included 1000 mg L?1 of formalin for 15 min (F1000), Treatment 3 included povidone–iodine of 50 mg L?1 for 15 min (PI50), Treatment 4 included povidone‐iodine of 100 mg L?1 for 10 min (PI100) and Treatment 5 involved a control with no chemical treatment (CONT). For each treatment, the per cent egg hatching rate, per cent survival to first feeding and notochord length at the time of hatching to the nearest 0.1 mm were recorded. Bacteria were also cultured from eggs after treatment to determine the effectiveness of each treatment in reducing the bacterial counts (CFU mL?1). Treatments F100, F1000 and CONT yielded the highest hatch rates for each species (70–80%), whereas treatments PI50 and PI100 yielded the lowest hatch rates (0–2%). There were no significant differences in survival to first feeding or notochord length, which suggests that the disinfection treatments did not have a negative effect on the yolk sac larvae. The PI50 and PI100 treatments had the lowest bacterial colony counts, showing almost zero bacterial growth. The highest bacterial growth occurred in the F100, F1000 and CONT treatments. Based on the results from this study, the F100 treatment provided the best balance of disinfection and larval health for CYT, WSB and HA.  相似文献   

6.
The efficacy of four chemical reagents, iodophor, formalin, hydrogen peroxide and bronopol as fish egg surface disinfectants were evaluated in bluefin sea bream (Sparidentex hasta). Fertilized eggs were counted and subjected to a static bath dip treatment in different concentrations of the above chemicals for 4 min before being incubated at 20 ± 0.5°C for 40 h. Treatment efficacy of the different disinfectants was evaluated by assessing the bactericidal activity, egg hatch percentage and survival of larvae up to 3 days post hatch. Results showed that iodophor at medium concentrations (75 and 100 ppm) was the best of all tested disinfectants in bacterial killing ability (12% reduction in the bacterial counts), egg hatching per cent (99.8% and 99.6% respectively) and larval survival up to 3 days post hatch (50.8% and 54.8% respectively). Formalin was the second best disinfectant at levels of 100 and 150 ppm. Hydrogen peroxide gave good results compared with the control while, bronopol showed discouraging results. In conclusion, iodophor appeared to be suitable for bluefin sea bream eggs disinfection with a 4 min exposure to 75–100 ppm when applied 14–16 h after egg fertilization.  相似文献   

7.
Elimination of egg stickiness is an important factor in artificial reproduction of pikeperch (Sander lucioperca L.). This study was conducted to evaluate the effectiveness of Alcalase enzyme to remove the adhesive layer of pikeperch eggs. The eggs were treated with Alcalase at 0.5, 1.0, 1.5, 2.0 and 5.0 mL L?1 or a milk/talc solution 2 min post insemination. Duration of exposure was 2 min in Alcalase and 60 min in milk/talc. The highest, albeit not significant, hatching rate (85.4%) was found with 1.5 mL L?1 of Alcalase, but hatching rates were similar in 0.5, 1.0 and 2.0 mL L?1. Hatching rates were significantly lower groups treated with 5.0 mL L?1 Alcalase enzyme (56.4%) compared to groups treated with milk powder and talc (61.3%). Nominally complete removal of adhesiveness was observed in 1.5 and 2 mL L?1. All Alcalase treatments led to significantly lower incubation duration compared with the traditional milk/talc treatment. The application of Alcalase successfully eliminated pikeperch egg stickiness in less time than with traditional milk/clay/talc methods.  相似文献   

8.
The aim of this study was to evaluate the effect of hydrogen peroxide, iodine solution (PVP) and methylene blue on eggs disinfection of three ornamental fish species, Danio rerio, Pterophyllum scalare and Gymnocorymbus ternetzi. The main idea was to create conditions to enhance the hatching rates. Eggs of each species were exposed to different concentrations of hydrogen peroxide (5, 10, 15 and 25 mg/L), PVP (0.25, 0.5, 0.75 and 1 mg/L) and methylene blue (0.5 1, 2 and 3 mg/L). The optimal doses ranged between species and chemicals: for G. ternetzi, the concentrations that high enhanced the hatching rate were 1 mg/L for the PVP treatment, 25 mg/L for the hydrogen peroxide treatment and 3 mg/L for methylene blue treatment; for P. scalare, the best results were achieved with 25 mg/L for hydrogen peroxide treatment and 3 mg/L for methylene blue treatment. By contrast, for all the different chemical did not increased the D. rerio hatching rate. Results showed that hydrogen peroxide and methylene blue are the most versatile, effective and safe to use in these species. On the other hand, PVP can be used but with many precautions due to very low safety margin. Results clearly show that the optimal concentration of chemicals for eggs disinfection is fish species dependent and it is completely wrong to extrapolate concentrations between different chemicals and fish species. Our study suggests that P. scalare can be used as a model in study of effectiveness of new chemicals with potential to disinfect water and increase hatching rates.  相似文献   

9.
Pinfish (Lagodon rhomboides Linnaeus) and pigfish (Orthopristis chrysoptera L.) are relatively new, cultured species commonly used as marine baitfish in the south‐eastern United States and currently have no defined protocols for egg incubation. Thus, experiments were conducted to determine efficient egg stocking densities during static and flow‐through incubation that yielded higher quality larvae. Eggs of each species were incubated statically at 250, 500, 1000 and 2000 eggs L?1, and after incubation, egg hatching success, larval survival to first feeding, larval morphometrics and water quality were assessed. Stocking densities above 250 eggs L?1 led to significant reductions in pinfish hatching success and water quality degradation, evident from decreased dissolved oxygen and pH levels and increased nitrogenous wastes. Increased stocking densities for pigfish also resulted in significant water quality degradation, although hatching success was unaffected up to a density of 1000 eggs L?1. A high flow‐through water exchange rate of 2000% daily resulted in significant reductions in nitrogenous wastes and greater stability in dissolved oxygen and pH levels during incubation when compared to static treatments of the same egg density. Additionally, the high exchange rate of 2000% was critical in maintaining high hatching success and larval survival to first feeding at stocking densities of 1000 eggs L?1 for pinfish and up to 4000 eggs L?1 for pigfish. No clear patterns in larval morphometrics were observed among stocking densities. Static incubation densities of 250 and 1000 eggs L?1 are recommended for pinfish and pigfish, respectively.  相似文献   

10.
Almaco jack (Seriola rivoliana Valenciennes) is an excellent candidate for aquaculture due to its fast growth rate and high market value. While S. rivoliana have adapted well to captivity, survival at early life stages can be improved to increase profitability during production. A wide range of variables cause larval mortalities but high bacterial loads in rearing tanks are often correlated with these losses. The aim of this study was to investigate the effect of egg disinfection on bacterial load and hatch rate of S. rivoliana. Disinfectants tested included formalin (F100 and F200; 100 and 200 mg/L, respectively, for 60 min), hydrogen peroxide (HPO; 300 mg/L for 10 min) and peracetic acid/hydrogen peroxide (PAA/HPO; 15.7 mg/L/39.6 mg/L for 1 min). Concentrations and contact times were determined based on current use in marine aquaculture and preliminary trials. Eggs treated with HPO and F100 had significantly higher hatch rates than the untreated control group. All treatments significantly decreased total Vibrio counts compared to untreated eggs; however, total bacterial counts were only decreased following treatments with PAA/HPO and F200. To prevent egg mortality due to bacterial overgrowth, consideration should be given to the use of surface disinfection using HPO or F100. Future studies should investigate the use of peracetic‐based products at lower doses.  相似文献   

11.
ABSTRACT:   To protect chum salmon eggs from water mold infection during incubation, the eggs were treated daily with sodium hypochlorite solution (NaOCl) at 10 mg/L residual chlorine concentration for 15 min during their developmental period from fertilization to eyed stages. The number of infected eggs and number of eyed eggs were observed on day 23 of incubation. The percentage of infected eggs to total eggs was significantly lower with NaOCl treatment (1.8 : 33.4%) than in the control (11.3 : 59.3%, P  < 0.01). The percentage of eyed eggs to total eggs was significantly higher with NaOCl (85.9 : 98.6%) than in the control (66.1 : 97.5%, P  < 0.01). The antifungal activity of NaOCl resulted in improving egg survival. Accordingly, NaOCl is a useful antifungal agent against water mold infection on chum salmon eggs.  相似文献   

12.
In an effort to optimize the efficiency of high‐density incubation of Atlantic cod Gadus morhua and haddock Melanogrammus aeglefinus eggs, the per cent hatch of eggs treated with four disinfectants (3% hydrogen peroxide, 1% polyvinylpyrrolidone iodine, 0.1% sodium hypochlorite and a 0.005% antibiotic solution – penicillin/streptomycin) was compared in both species. The per cent hatch of eggs of each species was greatest after a 24 h treatment with the antibiotic solution. The hatching success of eggs treated within the different disinfectant treatments depended upon the embryonic developmental stage in both species. The sodium hypochlorite treatment had the lowest % coverage of colony growth after disinfected haddock eggs were plated onto sterile agar media, highest survival rates to the end of the embryonic period, but the lowest per cent hatch.  相似文献   

13.
Hydrogen peroxide has been the only medicine used to treat salmon infected with sea lice [Lepeophtheirus salmonis (Krøyer)] on many farms in Scotland since 1992 and reports have suggested reduced treatment efficacy. The present study tests the sensitivity of sea lice to exposure to hydrogen peroxide under farm conditions and also in vivo by comparing lice from a farm with suspected resistance and lice from a farm that had not been pre‐exposed to hydrogen peroxide. In bin treatments on fish from a farm treated with hydrogen peroxide on 41 occasions, numbers of ovigerous lice declined by only 15% and 16% in two replicates and other mobile stages by 25%. Where hydrogen peroxide had not been used, ovigerous females declined by 90% and 87% and other mobile lice stages by 97% and 99%. These trials and observed poor efficacy of cage treatments, for example only 7.5% reduction in lice numbers when fish were treated with 2000 p.p.m. for 20 mins, indicated resistance of lice to hydrogen peroxide. The mechanisms involved in the development of resistance, possible genetic selection for lice with reduced carapace permeability or detoxifying enzymes such as catalase, or tolerance through induction by subtherapeutic exposure are reviewed. Implications for lice control strategies relying on hydrogen peroxide are discussed.  相似文献   

14.
In this study, we analysed the effect of population density and food concentration on the fecundity of a Mediterranean strain of Acartia tonsa to maximize egg production. During 4‐day feeding experiments, egg hatching success and faecal pellet production were also followed. The algae Rhinomonas reticulata was supplied at different concentrations corresponding to 250, 500, 1000, 1500, 2000 and 3000 μg C L?1 day?1 at the following adult copepod density: 40, 80 and 160 ind. L?1. Our results show a positive relationship between algal concentration and egg production under all experimental conditions confirming that the quantity of food strongly limits A. tonsa fecundity. Maximum egg production (57 eggs per female) was reached at the lowest density and at the maximum food concentration. Percentage of egg hatching success was not dependent on the quantity of food used. At the same food concentration, an increase in population density from 40 to 80 ind. L?1 induced an increase in faecal pellet production per couple which did not correspond to an increase in egg production, suggesting that higher energetic costs were shifted to swimming activity. Productivity of the A. tonsa Mediterranean strain is mainly limited by the quantity of food rather than by crowding conditions.  相似文献   

15.
Cultivated Atlantic cod (Gadus morhua) entering their first year of gamete maturation were fed diets with different levels of arachidonic acid (ARA) and eicosapentaenoic acid (EPA) for 6.5 months prior to commencement of spawning. Gravid females were stripped three times: at the beginning, peak and end of spawning. Lipid composition and egg and larval quality of 34 family crosses were investigated. Results indicated that ARA uptake into eggs from broodstock diet was highly efficient achieving proportions of ARA up to 84% higher in eggs than in the diet. EPA was 42–76% higher, and DHA was 155–173% higher in eggs than in diets. Cod fed the diet with the lowest EPA/ARA ratio had the greatest egg production. Eggs from fish on a diet with high ARA level had significantly higher fertilization and hatching success than those fed low levels of ARA. This diet produced on average 71 viable eggs g?1 female compared with 32.5 and 4 eggs in diet B and C, respectively. Furthermore, larval survival until 8 days posthatch was higher in diets with lower ARA levels. The combined results showed that ARA dietary supplementation and low EPA/ARA ratio yielded a greater number of viable larvae kg?1 female.  相似文献   

16.
不同消毒剂对三种鲑科鱼受精卵成活率的影响   总被引：1，自引：0，他引：1  
在水温4.5±1.3℃下和桶式流水孵化器中,研究了不同浓度过氧化氢水溶液、聚维酮碘、甲醛溶液和二氧化氯对虹鳟（Oncorhynchus mykiss）、金鳟（Oncorhynchus mykiss）和白斑红点鲑（Salvelinus leucomaenis）受精卵至发眼期胚胎的成活率和防治水霉菌等感染的效果。结果表明：二氧化氯处理组与对照组鱼胚胎的发眼率与畸形率差异显著;聚维酮碘处理组鱼胚胎的发眼率虽与对照组无显著差异,但畸形率明显高于甲醛对照组。因此,聚维酮碘和二氧化氯不适于这三种鱼受精卵的消毒。1000 mg.L-1的过氧化氢饱和水溶液（双氧水）与1500 mg.L-1甲醛处理组鱼胚胎的在发眼率无显著差异,但随着药物浓度的增加,其畸形率显著高于对照组。因此,建议鲑鳟鱼受精卵孵化过程中可用1000 mg.L-1双氧水防止水霉菌滋生,提高受精卵的成活率。  相似文献   

17.
Within the State of Maine, only a portion of the farm sites experience sea lice (Lepeophtheirus salmonis) infections on an annual basis. There has been concern about the further spread of lice by farming activities to unaffected areas despite routine disinfection of equipment with sodium hypochlorite or iodophors. We examined the effects of Povidone‐iodine, sodium hypochlorite and desiccation on egg strings of L. salmonis and the potential of these methods for preventing hatching of nauplii or development to the copepodid stage. L. salmonis egg strings were exposed to one of eight treatments: 200 ppm of sodium hypochlorite or Povidone‐iodine solutions for 1 min, 500 ppm of either disinfectant for one minute or 10 min, or desiccation for either 4 or 24 h. The egg strings were then incubated and the hatched copepods were kept for 6 days in filtered natural seawater at 32 ppt salinity at 12°C. Desiccation for 4 or 24 h were the only methods that prevented L. salmonis nauplii from hatching or developing to the infective copepodid stage. Common disinfection procedures against pathogenic bacteria and virus were not found to be effective against L. salmonis eggs.  相似文献   

18.
Abstract. Gross energy, ash content and elemental composition of carbon, nitrogen and hydrogen in eggs of the gilthead seabream, Sparus aurata L., have been determined throughout several spawning seasons. Also, changes in the biochemical components during embryonic development have been analysed. Gross energy of seabream eggs was approximately 1 J per egg. Dry weight of individual eggs at fertilization varied from 39 to 50μg, the chorion accounting for about 20% of total dry weight. However, there were no differences in carbon, nitrogen, hydrogen and ash percentages. From fertilization to hatching eggs lost 7·2% of total energy (chorion not included). The possible relationship between egg energy content and recent emerged larvae is discussed.  相似文献   

19.
Abstract – Body length, age, egg size, embryo salinity tolerance and length at hatching of the freshwater (salinity <0.1 ppt, Lake Peipsi) and brackish-water (salinity 2–6 ppt, Pärnu and Matsalu Bay) ruffe, Gymnocephalus cernuus (L.), were examined to reveal their reproductive success in moderate salinity. Eggs of females originating from brackish water were significantly larger than eggs of freshwater females. No correlation between egg size and female size and age was found in brackish-water populations. In the freshwater population there was a small negative correlation between egg size and female size, but no correlation with female age. Fertilisation by sperm of males of different origin (brackish water or freshwater) produced no significant differences at any critical developmental stage (fertilisation, gastrulation, hatching) in the development of eggs from brackish-water or freshwater females at 3.3, 5.5, 7.7 and 9.9 ppt salinity. Survival rates in different salinity depended only on female origin; embryonic salinity tolerance was higher in ruffe inhabiting brackish water. Obviously, embryo salinity tolerance in ruffe is determined by egg qualities.  相似文献   

20.
Scanning electron microscopy indicated that stored resting eggs of the marine rotifer Brachionus plicatilis Müller were colonized by numerous bacterial cells that affect the hatchability of resting eggs. The effectiveness of chemical disinfectants on the hatching of the resting eggs was studied using selected chemicals and antibacterial drags. The hatching success rate of the fresh and stored eggs was 26 ± 5.8% and 0%, respectively. Sodium hypochlorite (1.0 p.p.m.) increased the hatching rate to 48 ± 1.3% in freshly-collected and 28 ± 1.8% in stored eggs. Physical disintegration of the bacterial mat occurred after 1 h of treatment with sodium hypochlorite. Among antibacterial drugs, sodium nifurstyrenate (Erubaju) enhanced the hatching success rate to 40 ± 1.2% and 20 ± 1.1% for the freshly-collected eggs and stored resting eggs, respectively. However, tetracycline and oxytetracycline did not significantly influence the hatching of the stored eggs. These observations are discussed in relation to the development of an improved method for the processing and hatching of rotifer resting eggs.  相似文献   

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