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1.
Juvenile channel catfish Ictulurus punctatus were exposed to 1× (0.44 mg/L), 3× (1.32 mg/L), or 5× (2.19 mg/L) the recommended therapeutic concentrations of waterborne potassium permanganate (KMnO4) for 36 h to determine the toxicity of the chemical. The fish were observed for 14 d after exposure. Gill, liver, and blood samples were collected before exposure, at 12, 24, and 36 h of exposure, and at 48-h intervals for 14 d thereafter. Analysis of homogenized gill tissue showed a transient increase in manganese content that quickly disappeared once exposure was discontinued. Fish exposed to the 3× and 5× concentrations of KMnO4 experienced 9 and 50.6% mortality, respectively. Plasma cortisol was elevated more than ten-fold at the 5× concentration. Both plasma chloride and osmolality were significantly reduced at the 3× and 5× concentrations but were unchanged at the 1×. Packed cell volumes (PCV) of whole blood rose significantly in response to 3× and 5× concentrations of KMnO4 Mortality may have been the result of blood electrolyte depletion as indicated by increased PCVs, loss of chloride, and reduced osmolality. All stress indicators measured, except PCV at the 5× concentration, were indistinguishable from unexposed controls within 48 h after exposure was discontinued. At the l× concentration (the concentration most like that employed in a disease treatment) no changes were observed in any stress indicators measured suggesting that KMnO4 may be safely used as a disease therapeutant for channel catfish.  相似文献   

2.
Abstract. An enzootic, Australian, atypical strain of Aeromonas salmonicida isolated from diseased goldfish, Carassius auratus (L.), was inoculated into Atlantic salmon, Salmo salar L., brown trout, S. trutta L., rainbow trout, S. gairdneri Richardson, and brook trout, Salvelinus fontinalis (Mitchill), fingerlings by intraperitoneal injection (i.p.) and by bath challenge, the latter with and without prior abrasion of skin. The 10-day LD50 (i.p.) was estimated to be 7·4 × 10-3 colony forming units (cfu) for Atlantic salmon, 3·0 × 10-2 cfu for brown trout, 3·7 × 102 cfu for brook trout and 6·4 × 103 cfu for rainbow trout. Brown, rainbow and brook trout succumbed to bath challenges with between 105–106 cfu/ml, developing ulcers of the skin and septicaemia. The organism was trasmitted from inoculated fish to five of 195 within-tank control fish via water and established a carrier state in one of 14 Atlantic salmon. It was concluded that the organism poses a significant threat to the salmonid farming industry and wild salmonid fisheries in Australia.  相似文献   

3.
Abstract –  Downstream movement of a wild population of brown trout was examined in a small Danish stream in relation to morphological and physiological smolt status from March to May. Downstream movement was monitored in a Wolf-type trap covering all possible passage routes in the stream. Trout caught in the trap were classified as parr, pre-smolt or smolt based on morphological criteria and compared with trout randomly caught by electrofishing upstream of the trap. Representative gill samples from trap-caught and electrofished trout were analysed for gill Na+, K+-ATPase activity and used as a measure of physiological smolt status. Only a few parr occurred in the trap. Few pre-smolts occurred in the trap evenly in March and early April. In late April, pre-smolt movement peaked. By comparison, the main downstream movement of smolts occurred in distinct peaks through late March and April. The majority of fish caught in the trap were judged as pre-smolts or smolts based on morphological criteria's and they were characterised by relatively high gill Na+, K+-ATPase activity compared with trout judged as parr. Trout caught by electrofishing upstream the trap, were classified as parr, pre-smolts and smolts early in the season (March). During and after the main smolt-run in April the distribution of the remaining trout in the brook became skewed in favour of pre-smolt and parr. The study suggests that smolting trout initiate downstream movement once having reached a certain physiological smolt condition (judged by increased gill Na+, K+-ATPase activity).  相似文献   

4.
Abstract. Rainbow trout exposed to environmental free C02 concentrations ranging from 12–60 mg/1 for a minimum of 275 days developed nephrocalcinosis. Gross, histopathological and chemical examinations demonstrated that prevalence and severity of nephrocalcinosis increased with increasing CO2 concentrations. The condition was characterized by calcification and granuloma formation in kidney and stomach. Diet, but not water, PO4 -P concentration appeared to modify the prevalence and severity at each CO2 concentration tested.  相似文献   

5.
Abstract. The pathogenicity of Renibacterium salmoninarum to carp, Cyprinus carpio L., and rainbow trout, Salmo gairdneri Richardson, was investigated. All carp injected with 4·8 × 108 cells/fish, or 4·8 × 107 cells/fish survived for 38 days. R. salmoninarum was isolated from all moribund fish, but not from the kidney of surviving fish, although R. salmoninarum antigen was detected in several of these fish by the dot blot assay. On the other hand, mortality in rainbow trout was 95% in the fish injected with 4·8 × 108 cells/fish, and 15% in those which received 4·8 × 107 cells/fish. R. salmoninarum antigen was detected by the dot blot assay in all surviving rainbow trout. The number of R. salmoninarum cells was immediately decreased by carp or rainbow trout serum, and the serum bactericidal activity of carp was higher than that of rainbow trout. Carp blood leucocytes had higher phagocytic activity than those of rainbow trout.  相似文献   

6.
Juvenile red drum Sciaenops ocellatus were tank-reared in two, separate 30-d trials to assess effects of total water hardness and chloride concentratlon on growth, survival, and feed conversion. Two levels of total hardness and chloride were used in 2 × 2 factorial designs to obtain total hardness and chloride levels in trial one of 100 and 200mg/L CaCO3 and 125 and 250mg/L Cl−, and hardness and chloride levels of 100 and 400mg/L CaCO3 and 150 and 500mg/L Cl− in trial two. In trial one, average daily growth and feed conversion were significantly ( P ≤ 0.05) improved at 100mg/L hardness levels compared to 200mg/L at both chloride levels. Average daily growth was 0.11 ± 0.02g/d at 100mg/L hardness and 125mg/L Cl− compared to 0.06 ± 0.01g/d at 200 mg/L hardness and 125mg/L chlorides. No significant ( P ≥ 0.05) difference in survival could be attributed to levels of total hardness or chloride. In trial two, 500 mg/L Cl− treatments produced significantly ( P ≤ 0.01) better growth, survival and feed conversion than 150mg/L Cl− at either level of total hardness (100 and 400mg/L). Survival at 150mg/L chloride and 100mg/L hardness was 48.8 ± 18.7%, while at 500mg/L chloride and 400mg/L hardness survival increased to 96.6 ± 2.1%. Growth also increased from 0.14 ± 0.03 to 0.27 ± 0.01g/d and feed conversion improved from 5.77 ± 1.56 to 1.87 ± 0.06 at the same levels. No interactions between levels of hardness or chlorides were shown to affect red drum growth, survival, or feed conversion in either trial.  相似文献   

7.
Abstract.— In an effort to feed sunshine bass Morone chrysops × M. saxatilis efficiently, promote optimal growth, and reduce labor costs associated with feeding, sunshine bass were grown in cages and fed one of four feeding frequencies: once/d, twice/d, once every other day (I X/EOD), and twice every other day (2X/EOD) for 21 wk. Juvenile sunshine bass were fed a commercial floating diet containing 40% protein and 11.5% lipid. One hundred fish were hand-counted and stocked into each of 12 3.5-m3 cages with three replications per treatment. At the conclusion of the study, percentage weight gain of sunshine bass fed twice/d was significantly (P < 0.05) higher (1,850%) compared to fish fed all other feeding frequencies. Specific growth rate (SGR) of fish fed twice/d was significantly higher (2.1%/d) compared to fish fed all other feeding regimes, while fish fed once/d had a higher SGR (2.0%/d) compared to fish fed I X/EOD (1.6%/d) and 2X/EOD (1.8%/d). Percentage survival was not significantly different (P > 0.05) among all treatments and averaged 70.4%r. Feed conversion ratio (FCR) of fish fed twice/d was significantly higher (2.40) compared to fish fed all other feeding regimes. Percentage fillet weight of fish fed twice/d was significantly higher (27.8%) compared to all other treatments. Percentage moisture, protein, lipid, and ash in fillet were not significantly different among all treatments and averaged 75.7%, 19.4%, 3.5%, and 1.2%n, respectively (wet-weight basis). Based upon data from the present study, it appears that producers growing juvenile sunshine bass in cages may want to feed fish twice daily. This feeding regimen allows for higher growth rates, without adverse effects on body or fillet compositions. However, economic analysis needs to be conducted to determine if feeding twice/d is profitable.  相似文献   

8.
Abstract. A natural bath challenge method has been developed for furunculosis using Atlantic salmon, Salmo salar L., and rainbow trout, Salmo gairdneri Richardson. Fish were placed in an enclosed, continuously circulating tank system, supplemented with additional oxygen, the temperature raised gradually (overnight) to 15–16°C, a low dose of Aeromonas salmonicida (strain 184/186) introduced into the tank and the challenge maintained for 14 days. The challenge strain was characterized with respect to possible virulence factors and possessed an A-layer, ability to auto-agglutinate, haemagglutinate, adhere to Atlantic salmon cells and resist destruction by serum. No caseinase activity was detected. LD50 for salmon using this method was 1.8×103 cells per millilitre while trout had an LD50 of 9.5×104 cells per millilitre. Onset of the disease appeared to depend on fish size with larger trout (50 g) taking up to 10 days to show signs of the disease while mortalities in smaller trout (8.5g) commenced on day 1 post-challenge.  相似文献   

9.
A 10-wk growth comparison trial of two strains of channel catfish Ictalurus punctatus was conducted in 40 120-L flow-through aquaria using a 2 ± 2 × 2 factorial experiment design. The three factors evaluated were: strain (Norris and NWAC103), dietary protein level (28% and 32%), and feeding rate (restricted and satiate). Average initial weight (× SD) for the Norris strain was 3.0 ± 0.08 g/fish, while that of the NWAC103 strain was 4.7 ± 0.13 g/fish. The feeding rate for the satiated group was adjusted based on feeding observations. The feeding rate for the restricted group was adjusted to about 2/3 of the satiate level. For both satiate and restricted feeding regimens, the NWAC103 strain consumed more feed than the Norris strain. Fish of Norris strain fed the 32% protein diet consumed more feed than fish fed the 28% protein diet; however, there were no differences in feed consumption in the NWAC103 fish fed the two protein diets. Regardless of feeding rate, the NWAC103 fish gained more weight and converted feed more efficiently than the Norris fish. Fillet composition was not affected by fish strain. Fish fed the 28% protein diet had a lower level of fillet protein than fish fed the 32% protein diet. In fish fed to satiation, a 32% protein diet resulted in a lower fillet fat level than a 28% protein diet, but no differences were observed in fillet fat levels between fish fed the two dietary protein levels for the restricted group. Results from the present study demonstrate that under laboratory conditions, the NWAC103 strain of channel catfish is superior to Norris strain in feed consumption, growth rate, and feed efficiency. Our data also indicate that either a 28% or 32% protein diet can be fed to either strain of channel catfish whether they are fed to satiation or fed a restricted ration with no detrimental effects on growth.  相似文献   

10.
Haemorrhagic areas in the mouth of farmed turbot, Scophthalmus maximus (L.)   总被引：4，自引：0，他引：4  
Abstract. An epizootic in juvenile turbol reared on a farm located in The Ria de Vigo, Galicia, Northwest Spain, is described. The diseased turbot did not display unusual swimming behavior; the external signs of the disease were abdominal distension and haemorrbagic areas in the mouth. Internal examination of the fist showed an accumulation of reddish fluid in the peritoneal cavity. Microbiological analysis of the diseased fish revealed the presence, in pure culture in all the organs and lesions examined, of a bacterium which was characterized biochemically as Vibrio splendidus biotype I. The virulence tests showed that the V. splendidus biotype I isolate was pathogenic for rainbow trout (LD50: 2.2 × 104) and also for turbot (LD50: 1.2 × 104). The treatment of the fish using flumequine incorporated into the feed was effective in offsetting the mortality rate.  相似文献   

11.
Abstract. Infection trials using two serotypes of VHS viruses (type 1 and 23/75) demonstrated that Atlantic salmon fry were susceptible to the disease when injected intraperitoneally (i.p.) with 103 pfu of virus/fish but resistant to infection by a bath method when exposed for 3 h in water containing 5 × 104 pfu of virus/ml. In the i.p.-infected fish, mortality reached 78 and 67% within 13 days with VHSV1 nad 23/75 serotypes, respectively. High virus yields were recovered from infected fish and virus shedding was demonstrated by the onset of VHS in rainbow trout kept in the outflow water from the aquaria containing infected salmon. Neither mortality nor virus shedding occurred in salmon infected by the water route but virus multiplication was demonstrated in 2 of 60 fish with VHSV1 and 3 of 60 fish with virus 23/75. On day 79 post-infection the sera from surviving salmon of both i.p. and bath infection trials exhibited good neutralizing titres (around 1000) against the homologous viruses.  相似文献   

12.
Rainbow trout Oncorhynchus mykiss fry were reared at four densities ranging from 10,800 to 43,926 fish/m3 (9.91 to 37.60 kg/m3) during an initial feeding period of 35 d. Each of the four initial density treatments were then split into high (3,780 fish/m3) and low (1,890 fish/m3) density groups and reared in outdoor raceways for an additional 74 d. A necropsy-based general health and condition assessment indicated that hematocrit, plasma protein, and the thymus index were significantly elevated in the outdoor high density group. Changes in these variables were unrelated to the initial rearing density, except for plasma protein which decreased as the initial density increased at low densities. Other necropsy variables indicated normal, healthy fish. Agonistic behavior was assessed at 4, 9 and 13 wk of age by observing the number of aggressive chases in paired and group (five fish) trials. The number of chases generally increased with age, although the difference between 9 and 13 wk was variable. Feeding did not elicit more chases in this study except for 9-wk-old fry. Initial rearing density did not have any impact on the number of chases at 4 or 13 wk, but at 9 wk the number of chases increased with initial density for the group tests. Relative fin length measurements of all fins except the adipose indicated no combination of initial density and outdoor density was superior to another for reducing fin erosion. This study indicated that rainbow trout fry may be reared at initial densities approaching 44,000 fish/m3 (Piper density index of 1.1) without negatively affecting growth and fin condition or inducing higher levels of agonistic behavior later on.  相似文献   

13.
Benthic respiration in two fish culture ponds at Comayagua, Honduras, was below 1g CO2/m2 per day during culture periods. When ponds were drained for fish harvest, bottom soils were exposed to the air, and soil respiration rates as high as 10g CO2/m2 per day were recorded. High rates of soil respiration following removal of saturated conditions declined as labile organic matter was consumed and soil moisture content declined. Laboratory studies showed that the moisture content greatest for soil respiration was near saturation, and either drying soils or completely saturating them drastically reduced respiration. Although soil respiration rates were much greater during the fallow period than during the culture period, more organic matter was decomposed during the culture period because it was much longer (5 months) than the fallow period (2 weeks).  相似文献   

14.
Effects of three sublethal levels of cadmium (40, 120 and 260 μg L−1) on apparent total dry matter (TDM) and apparent protein (PD) digestibility in goldfish, Carassius auratus (L.), over an 8-week experimental period were investigated using diets with and without chromic oxide (0.5%) marker. The %TDM and %PD were estimated based on crude fibre as the marker for the diet without Cr2O3, and Cr2O3 and crude fibre as markers for the diet with Cr2O3. Generally, digestibility estimations were lower in goldfish fed the diet with the Cr2O3 marker. Similarly, for the diet with Cr2O3 marker, digestibility estimates based on crude fibre were higher than those based on Cr2O3. In all treatments (2 diets × control and 3 cadmium levels), the weekly estimations of %TDM and %PD did not differ significantly ( P > 0.05). The effect of cadmium on weekly %TDM and %PD was not that obvious in all treatments. However, the overall mean %TDM and %PD differed significantly ( P < 0.05) between diets and between markers, at all cadmium concentrations. The present study raises doubts regarding the validity of the use of Cr2O3 as a marker in digestibility studies in fish, as had been recently suggested by other authors but for different reasons.  相似文献   

15.
A selection of 16 field isolates of Photobacterium damselae from marine rainbow trout farms in Denmark was subjected to phenotypic and genotypic characterization and pathogenicity to fish. All isolates belonged to the subspecies damselae , being positive for haemolysis, motility and urease. There were considerable differences in haemolytic properties, some isolates presenting a broad zone of haemolysis and others only a narrow zone. Pulsed-field gel electrophoresis revealed a high diversity indicating that P. damselae subsp. damselae is an opportunistic, not clonal pathogen in Danish marine rainbow trout. Virulence of the strains to rainbow trout was highly variable with LD50 values ranging from 3.9 × 103 to 1.5 × 108 cfu at 20 °C. The virulence was significantly higher at 20 °C than at 13 °C. The strains with the strongest haemolytic properties were the most virulent suggesting a strong involvement of haemolysin in the pathogenesis. The pathological changes were consistent with a bacterial septicaemia and the haemorrhages were more pronounced than for most other bacterial infections.  相似文献   

16.
We studied the effect of genistein, a weak estrogenic compound found in soybean products, on the growth and reproductive development of yellow perch Perca flavescens . Four diets were prepared: control, estradiol-17β (E2) at 10 μg/g diet (E10), and genistein at 7.5 and 0.75 mg/g diet (G7.5 and G0.75). Fish (initial weight = 13–15.5 g and initial total length = 105–111 mm) were fed to excess for 63 d. The E10 diet promoted weight gain in yellow perch of both sexes, whereas the G7.5 diet decreased weight gain in females. The growth of the G0.75 group was not different from either the E10 group or the control group. Among females, fish fed the E10 diet had the lowest plasma concentration of E2 36 h after the last feeding of the study. The plasma concentration of E2 did not differ among the males from the four treatments. The E10-treated fish of both sexes had increased plasma concentration of alkali-labile phosphoprotein phosphorous (ALPP) in both sexes, indicating that vitellogenesis had been induced. Neither genistein diet increased plasma (ALPP) concentration. Male but not female yellow perch fed the E10 diet had significantly lower gonadosomatic indices compared to control and genistein groups. These results suggest that genistein may have a positive effect on growth in yellow perch, but no apparent estrogenic effects on reproductive function.  相似文献   

17.
Abstract. The morphometric relationships, standard length-weight, standard length-width and weight-width for Cichlasoma urophthalmus (Günther) in the weight range 0.78-262g were: log10 weight =−4.35 + 2.95 × (log10 standard length); log10 width =−0.73 + 0 99 × (log10 Standard length) and log10 width = 0.74 + 0.33 × (log10, weight). Two box graders were designed and tested based on these data. The operation efficiency (expressed as a percentage of the sample used to test it) was 96.1 % and 95% for the two graders. Results indicated a tendency to undergrading (small fish detained by the bars) by the first grader and overgrading (large fish going between the bars) by the second, the latter as a result of the major variability in the body shape from fish as they grow. The results are satisfactory, and larger graders for commercial use could be constructed based on these relationships.  相似文献   

18.
Cross-breeding was investigated as a strategy to improve performance of the Australian native freshwater fish, silver perch ( Bidyanus bidyanus Mitchell) through the exploitation of heterosis during the fingerling phase of production. Growth, and mid and best parent heterosis of two wild strains, Cataract Dam (C♂× C♀) and Murray River (M♂× M♀) and their reciprocal crosses (C♂× M♀ and M♂× C♀) were evaluated in cages and ponds through summer, and in tanks in a re-circulating aquaculture system during winter. The M × C cross grew significantly faster than the reciprocal cross and pure strains in cages and tanks, had the lowest coefficients of variation of weight and length and was 20.9% and 16.0% heavier than mid-parent and best-parent average, respectively, when grown in ponds. Differences in growth between the reciprocal crosses were also evident, with C × M expressing significantly less heterosis in cages and tanks. Faster growth of M × C was attributed to greater appetite; however, at sizes approaching 250 g this feeding vigour diminished. The results of this study suggest that use of the M × C cross has the potential to reduce the length of the culture period and lower costs of silver perch production.  相似文献   

19.
Acceptance and Consumption of Food by Striped Bass and Hybrid Larvae   总被引：1，自引：0，他引：1  
Food acceptance, consumption and weaning times were investigated for striped bass ( Morone saxatilis ) and hybrid striped bass ( M. saxatilis × M. chrysops ) larvae. Experimental treatments consisted of: control groups of striped bass (SC) and hybrids (HC) fed Artemia nauplii; hybrids fed formula food (HF); and hybrids weaned from Artemia nauplii to formula food at 11–15 days (HF1), and 18–22 days (HF2) posthatch. The formula diet did not support growth and resulted in total mortality of the HF hybrids by the third week posthatch. HF1 fish had significantly slower growth and lower survival than HF2 of HC. The HF2, HC and SC groups had similar growth and survival, which indicated no heterosis in hybrids. There were no differences in Artemia nauplii consumption by the SC and HC groups. Daily consumption increased exponentially for both groups (0.8 to 50–60 cal/day/larva between 7 and 30 days posthatch). Weight specific consumption (WSC) decreased initially and then increased for both groups. A mean WSC of 58% (range of 24–83%) was found for the combined SC and HC groups. Food conversion ratio, growth efficiency, caloric efficiency, and productive protein values were similar for striped bass and hybrid larvae.  相似文献   

20.
Abstract. Rainbow trout, Oncorhynchus mykiss (Walbaum), exposed to environmental nitrite for 3h showed significantly reduced chloride concentrations from 120·9 ± 0·5 to 113·8 ± 2-4 mmol/1, the result of nitrite uptake by the gills with a compensatory loss of blood chloride. This change could be prevented by injection of 10 mg/kg sulpiride, which stimulates prolactin secretion through antagonism of dopamine D2 receptors, thus increasing circulating prolactin levels. Prolactin is known to decrease membrane permeability and the increased levels of the hormone probably account for the relatively unchanged (compared to controls) plasma chloride and potassium levels in nitrite-exposed, sulpiride-treated fish.  相似文献   

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