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1.
Comparative evaluation of mahua (Bassia latifolia) oil cake (MOC) and castor bean (Ricinus communis) seed (CBS) was tested as piscicides for tilapia (Oreochromis mossambicus) and panchax (Aplocheilus panchax), and residual toxicity test was done on Labeo bata. Delayed response of CBS compared with MOC was evident as first and total mortality of tilapia was encountered at 4th and 10th hour of application, against 26 hr and 42 hr in panchax respectively. Susceptibility of the test fish to the piscicides was highly variable as tilapia was more susceptible than panchax under both the piscicides tested especially in CBS. Residual toxicity decreased polynomialy over time (R2 ≥ 0.99) and reduced to below 10% on day 13–14 in both MOC and CBS treatments. Both MOC and CBS contributed positively to the nutrient pool of water in which CBS provided more nitrogen compared with MOC. N: P ratio of water in CBS treatment increased exponentially to more than 18 indicating phosphorus limitation.  相似文献   

2.
Flavobacterium psychrophilum, the causative agent of bacterial cold‐water disease (BCWD) in freshwater‐reared salmonids, is also a common commensal organism of healthy fish. The virulence potential of F. psychrophilum isolates obtained from BCWD cases in Ontario between 1994 and 2009 was evaluated. In preliminary infection trials of rainbow trout juveniles, significant differences (0% to 63% mortality) in the virulence of the 22 isolates tested were noted following intraperitoneal injection with 108 cfu/fish. A highly virulent strain, FPG 101, was selected for further study. When fish were injected intraperitoneally with a 106, 107 or 108 cfu/fish of F. psychrophilum FPG 101, the 108 cfu/fish dose produced significantly greater mortality (p < 0.05). The bacterial load in spleen samples collected from fish every 3 days after infection was determined using rpoC quantitative polymerase chain reaction amplification and by plate counting. Bacterial culture and rpoC qPCR were highly correlated (R2 = 0.92); however, culture was more sensitive than the qPCR assay for the detection of F. psychrophilum in spleen tissue. Ninety‐seven per cent of the asymptomatic and the morbid fish had splenic bacterial loads of <2.8 log10 gene/copies and >3.0 log10 gene copies/reaction, respectively, following infection with 108 cfu/fish.  相似文献   

3.
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4.
Asian seabass (Lates calcarifer) has been recognized as an economically important aquaculture species which can be adapted to and cultivated in wide range of salinities. The number of freshwater intensive seabass farms in Thailand is increasing annually. Here, we first describe the susceptibility of Asian seabass, which were cultured in freshwater, to Streptococcus inae (SI) and their pathological changes. Three isolates of putative SI were identified using a combination of standard biochemical assays and species‐specific PCR prior subjected to in vivo challenge. Accumulated mortalities of the fish which received 107 CFU fish?1 of either SI1J, SI SGSA or SI2J were 90%, 90% and 100% at 7 days‐post infection (dpi), respectively, and mortalities increased sharply between 3 and 5 dpi. Clinical signs such as erratic swimming and opaque eyes were identified from a few infected fish, while most died rapidly without any abnormal signs. Histopathological manifestations were observed in the multiple organs (kidney, liver and brain). Haemorrhage, hyperhemia, cellular degeneration and inflammatory cells infiltration were commonly found within the internal organs. Notably, the formation of numerous encyst‐like lesion aggregated by eosinophilic cells, resembling macrophages, were typically found in the brain of the infected fish. Summarily, this study first revealed that freshwater reared Asian seabass is highly susceptible to SI infection and haemorrhagic septicaemia was a major pathological change that could be found in the infected fish.  相似文献   

5.
The long term effects of moderate elevation ORP (oxidation–reduction potential) around 300–320 mV on the growth, hematological parameters and the ability of European seabass (Dicentrarchus labrax) to react against bacterial infection was studied in recirculating aquaculture systems (RASs). Two RASs, one with a moderate ozonation (RAS-O3) and a control (RAS-C) were used in this experiment. After 60 days, seabass reared in the RAS-O3 were more able to react against a Vibrio anguillarum infection. It was in spite of the fact that seabass in the RAS-O3 showed decreased feed intake, feed conversion rate, growth rate and modified hematological parameters compared with the fish in RAS-C. It is obvious that an ORP level of 300–320 mV is too high for seabass to adapt in terms of the growth performance and the hematological parameters. However the increased ORP resulted in a better ability of the fish to react against bacterial infection. Our results strongly suggest that ORP for seabass in RAS should be elevated but not exceeding 300 mV and a slightly increased and well controlled ORP level (above 240–270 mV) has a positive effect on the disease resistance of fish. For the future, molecular methods could be utilized to identify which functional groups of microbe are contributing to the ORP effect and investigate how ORP influenced fish physiology in RASs.  相似文献   

6.
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7.
The effects of replacing fish meal with Caridina nilotica as a protein ingredient on growth performance, nutrient utilization, carcass, proximate composition and economic benefits in Nile tilapia (Oreochromis niloticus) culture was evaluated. Replacement of the FM with C. nilotica was done at 25%, 50%, 75% and 100% (D25, D50, D75 and D100) and the substitution effects was compared with the control diet (D0, 0% C. nilotica). After 140 days of culture, the best growth performance, nutrient utilization and economic benefits occurred in fish groups fed diets with 25% C. nilotica inclusion. However, growth performance in fish fed diets D50 and D75 were comparable with the control (P > 0.05). At 100% substitution level of FM with C. nilotica, the growth performance and fish survival was lower than control. Protein and lipid contents in the fish and their digestibilities were highest in diet D25 and decreased with increasing levels of substitution of FM with C. nilotica. This study demonstrate that utilization of local protein sources (C. nilotica) can be effectively used to replace up to 75% of FM in the diets without compromising growth performance, survival, nutrient utilization and economic benefits in O. niloticus culture.  相似文献   

8.
Asian seabass (Lates calcarifer) has been designated as a candidate species for open sea cage culture in India. A case of vibriosis in Asian seabass reared in open sea floating cages is reported. Haemorrhage and ulcer were observed grossly in the diseased fish. The pathogen, identified as Vibrio alginolyticus based on biochemical and molecular characterization, was isolated from liver, gill, kidney, brain and blood. Histological examination of the diseased fish showed congestion, haemorrhage and necrosis in vital organs. The LD50 studies showed that the organism was virulent to Asian seabass, and the LD50 value was 103.2 CFU g?1 fish.  相似文献   

9.
In this study, we investigated the toxic effects of ammonia‐N on the plasma and haematological parameters and histological structure of blunt snout bream (Megalobrama amblycephala) juveniles. The fish (initial weight, 14.79 ± 0.01 g) were randomly sorted into six tanks (200 L), and each tank was stocked with 40 fish for culture. The juveniles were exposed to two ammonia‐N levels—0 mg/L (control group) and 25 mg/L (experimental group)—and sampled at 0, 6, 12, 24, 48 and 72 hr, and then they underwent 96 hr of post‐exposure recovery. The results showed that ammonia‐N had significant effects on the plasma and haematological parameters. The treatment group showed increased cortisol, plasma ammonia and haematocrit levels and white blood cell count with increasing exposure time, up to 24 hr, and then the levels and count decreased. A significantly higher plasma glucose level was observed in the treatment group at 12 hr. After 96 hr of post‐exposure recovery, all parameter levels decreased to the control levels. The fish displayed histopathological alterations in the gills, liver and kidney. The results indicate that the severity of the lesions clearly differed among the organs, with the liver showing the most extensive damage, followed by the gills and kidney. Adverse effects to physiological indicators and histological structure increased with increasing exposure time before 24 hr. The fish showed self‐regulation; however, the histological structure could not recover fully, the gill tissue showed irreversible changes and the kidney tissue exhibited the worst recovery ability.  相似文献   

10.
The study was to investigate the effects of garlic (Allium sativum) powder on feeding attraction activity, growth performance and digestive enzymes of juvenile Japanese seabass, Lateolabrax japonicus (initial weight: 29.82 ± 0.24 g). Six concentration gradients (0, 5, 10, 15, 20 and 25 g/kg diets) were formulated for luring and feeding experiment. The results showed a clear attractive trend of garlic powder for L. japonicus. A 28‐day feeding experiment indicated garlic could reduce the feed conversion ratio (FCR) (p < .05). The content of the body crude lipid was significantly increased at 10–15 g/kg diet (p < .05). Digestive enzyme activities including trypsin, amylase (AMS) and lipase (LPS) in the intestine were the highest at 10 g/kg diet (p < .05). Overall, garlic powder provides a promising and effective method for Japanese seabass healthy culture by improving fish growth and digestive ability. The results of this research suggested the additive suitable dosage of garlic powder was about 10 g/kg diet.  相似文献   

11.
This study evaluates the in vivo apparent digestibility coefficients (ADC) of rendered animal by‐product fats in European seabass (Dicentrarchus labrax) juveniles. Diets contained fish oil (FOd), poultry fat (PFd) or mammal fat (MFd), from rendering animal by‐products, at 140 g/kg. Macronutrient and fatty acids ADCs were evaluated in quadruplicate tanks with fifteen 100 g fish. While total lipids ADCs (88%–90%) were unaffected, individual fatty acids ADC varied significantly among diets. Monounsaturated fatty acids ADCs were similar (94%–95%), saturated fatty acids ADCs were lowest in MFd (85% vs. 91% in PFd and FOd), and polyunsaturated fatty acids (PUFA) ADCs were lowest in PFd (96 vs. 97%–98%). Total n‐3 PUFA were better digested in FOd than in the other diets (98 vs. 96%–97%), while MFd had the highest total n‐6 PUFA ADC. FOd showed significantly higher EPA (20:5n‐3) and DHA (22:6n‐3) ADCs compared to the other test diets. The obtained results suggest that rendered animal fats can be considered feasible alternatives to fish oil in seabass. Nevertheless, that lack of EPA and DHA in land animal fats, combined with the reduced digestibility of these fatty acids, may compromise its dietary inclusion at high levels.  相似文献   

12.
Aeromonas salmonicida subsp. salmonicida (hereafter A. salmonicida) is the aetiological agent of furunculosis in marine and freshwater fish. Once A. salmonicida invade the fish host through skin, gut or gills, it spreads and colonizes the head kidney, liver, spleen and brain. A. salmonicida infects leucocytes and exhibits an extracellular phase in the blood of the host; however, it is unknown whether A. salmonicida have an intraerythrocytic phase. Here, we evaluate whether A. salmonicida infects Atlantic salmon (Salmo salar) erythrocytes in vitro and in vivo. A. salmonicida did not kill primary S. salar erythrocytes, even in the presence of high bacterial loads, but A. salmonicida invaded the S. salar erythrocytes in the absence of evident haemolysis. Naïve Atlantic salmon smolts intraperitoneally infected with A. salmonicida showed bacteraemia 5 days post‐infection and the presence of intraerythrocytic A. salmonicida. Our results reveal a novel intraerythrocytic phase during A. salmonicida infection.  相似文献   

13.
The aim of the present study was to evaluate the effects of essential oil extracted from bergamot (Citrus bergamia) peel on growth performance and health status of European sea bass juveniles (5.10 + 0.05 g). Test diets supplemented with 0.0%, 0.5%, 1.0% and 2.0% bergamot peel oil (BPO0, BPO0.5, BPO1 and BPO2) were fed to experimental fish for 60 days. At the end of the experiment, the best growth performance was obtained in the BPO0.5 and BPO1 groups (p < .05). No significances were found for haematological parameters including red blood cell count, haematocrit and haemoglobin concentration at the end of the feeding experiment. There were significant differences between the total protein, cholesterol, alkaline phosphatase and glutamic oxaloacetic transaminase (p < .05) between the BPO0.5 and BPO1 supplemented groups and the control group with no BPO addition. The addition of BPO showed significant differences in immune parameters such as lysozyme activity, total myeloperoxidase content, superoxide dismutase and glutathione peroxidase activity between BPO0 and BPO supplemented groups (p < .05). It might be concluded that dietary addition of 0.5%‐1% BPO could increase the growth performance and feed utilization with improved health status in sea bass juveniles.  相似文献   

14.
A 15‐week trial was carried out to estimate the effects of functional compound additives (FCA) on intestinal morphology and microbiome in Japanese seabass, Lateolabrax japonicus, fed diets with soybean meal (SBM) partially replacing fish meal (FM). The formulation of FCA was the mixture of antioxidant, immunopotentiator and Mintrex® trace elements. Four isonitrogenous (45%) and isolipidic (11%) diets, including FM42 (the control group without FCA), FM35 (15% FM protein substitution level with FCA), FM21 (50% FM protein substitution level with FCA) and FM21‐N (50% FM protein substitution level without FCA) were formulated. Quadruplicate groups of seabass (initial average weight 125.65 ± 0.60 g) were randomly handfed each diet twice daily in seawater floating cage. No significant differences were found in microvillus height (HMV) and muscular thickness (MT) of distal intestine among fish fed FM42, FM35 and FM21, whereas the HMV, MT and fold height (HF) in seabass fed FM42 were significantly higher than those of seabass fed FM21‐N (P < 0.05). Seabass fed FM21‐N had more obvious enteritis parameters such as tissue disruption, wider lamina propria and less mucosal fold than those in seabass fed FM21. High‐throughput sequencing technology of gut flora showed that Proteobacteria was the most dominant bacteria at phylum level among groups. There was no significant difference in relative abundance and composition of gut microflora among groups. In conclusion, supplementation of FCA might partially eliminate SBM‐induced enteritis, but the composition and relative abundance of intestinal microflora were not affected by dietary treatments.  相似文献   

15.
Cyprinid herpesvirus 3 (CyHV‐3) or koi herpesvirus (KHV) is a virulent viral infection in common carp and koi. The disease has caused global epizootic and economic loss in fish aquaculture and in the wild. Clinacanthus nutans (Burm. f.) Lindau is a well‐known medicinal plant used in Thai traditional medicine. Virucidal effects of the plant extract against human herpes simplex virus have been reported. In this study, C. nutans crude extract was tested for antiviral activities against CyHV‐3 in koi carp. Results showed effective antiviral activity against CyHV‐3 pre‐ and post‐infection. The 50% lethal concentration (LC50) of extract was higher than 5 mg/ml. The 50% effective dose (ED50) was 0.99 mg/ml, 0.78 mg/ml, 0.75 mg/ml and 0.71 mg/ml at 1, 2, 3 and 4 hr pre‐infection, respectively. The ED50 from post‐infection tests was 2.05 mg/ml and 2.34 mg/ml at 0 and 24 hr, respectively. These results demonstrated that crude extract expressed antiviral activity against CyHV‐3 and can be applied as a therapeutic agent in common carp and koi aquaculture.  相似文献   

16.
Streptococcus iniae is one of the most serious aquatic pathogens, causing significant economic losses in marine and freshwater species, including Asian seabass (Lates calcarifer). Controlling this gram‐positive bacterial pathogen has been an issue in aquaculture systems, due to the combined effects of aquaculture intensification and climatic impacts. To date, there have not been any genetic parameter estimates for S. iniae resistance in Asian seabass. The main aim of this study was to examine genetic variation in S. iniae resistance and its genetic correlations with growth and cannibalism in Asian seabass families produced from a breeding programme for high growth in 2016 and 2017. The study included a total of 5,835 individual fish that were offspring of 41 sires and 60 dams (31 half‐sib and 34 full‐sib families). The experimental fish were challenged by intraperitoneal injection with a volume containing 105 CFU (colony‐forming unit)/fish. Resistance to S. iniae was measured as survival rate at 6 hr, 3, 5, 7, 10 and 15 days post‐challenge test. There were significant variations in S. iniae resistance among families at different observation periods (ranging from 24.4% to 80%). Restricted maximum‐likelihood method and mixed model analysis were applied to estimate heritability for S. iniae resistance. The heritability for S. iniae resistance ranged from 7% to 18% across different statistical models used. The common full‐sib effects accounted for 0.1%–2% of the total variation in resistance to S. iniae. Genetic correlations of the S. iniae resistance at 6 hr and 3 days with later post‐challenge test periods were low to moderate. However, these estimates for S. iniae resistance between successive measurement times (5, 7, 10 and 15 days) were high and close to 1. The genetic correlations of resistance with body weights at 180, 270 and 360 days post‐hatch were not significant as well with cannibalism. It is concluded that there is substantial additive genetic variation in resistance to S. iniae, suggesting there is potential for genetic improvement of Asian seabass for resistance to S. iniae through selective breeding.  相似文献   

17.

Nursery rearing is the critical interim phase in farming of Asian seabass fish (Lates calcarifer), which produce fish fingerlings as an input for grow-out farming. The present study evaluated the techno-economic performance of seabass nursery rearing in low and high saline coastal waters. The results indicated that seabass nursery rearing is technically efficient with a mean technical efficiency of 99.83% and 92.45%, respectively under low and high saline conditions. The mean survival of young fishes was 63.50% and 42.50% with a mean daily weight gain of 0.08 g and 0.15 g, respectively in low and high saline waters. While the benefit cost ratio (BCR) was 2.76 and 1.9, the internal rate of return (IRR) was calculated to be 300% and 130%, respectively, indicating the economic viability of nursery rearing under different salinity regimes. Furthermore, it was observed that nursery rearing in low saline waters was more efficient and highly remunerative. In the Indian socio-economic scenario, a mean monthly income per person spending 2 h per day was found to be 129 USD and 317 USD respectively in high and low saline nursery systems which is a considerable earning. The results explicitly stated that nursery rearing itself is an exclusively livelihood development activity for the coastal fisher families with an active participation of fisher women. Establishment of finfish hatcheries to ensure continued supply of seabass seeds is the key factor in facilitating wider adoption of nursery rearing as a sustainable farming activity.

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18.
Up to date, the carnitine palmitoyltransferase (CPT) system in fish nutrition receives little attention. The present study compared CPT I kinetic behaviour of Synechogobius hasta (carnivorous) and Ctenopharyngodon idella (herbivorous). The optimal conditions (temperature, incubation time, mitochondrial protein concentration and pH) for maximum CPT I activity showed no significant difference between S. hasta and C. idella. CPT I activities in S. hasta were significantly higher than those in C. idella. Affinity constants (Km) for carnitine in liver, heart, white muscle and spleen of S. hasta were significantly higher than those in C. idella. Km for palmitoyl‐CoA in liver and heart of S. hasta were significantly higher than those in C. idella. Vmax for carnitine and palmitoyl‐CoA in S. hasta tended to be higher than those in C. idella. Catalytic efficiencies (Vmax/Km) for carnitine in liver, white muscle and spleen of C. idella were significantly higher than those in S. hasta. Vmax/Km values for palmitoyl‐CoA in liver and heart of C. idella were higher than those in S. hasta. Our study demonstrated that the lower catalytic efficiency for carnitine in liver of S. hasta indicated that the fish showed a low capacity for energy generation through β‐oxidation of long‐chain fatty acids, which easily caused fatty liver syndrome. This is the first study in which, by using carnitine and palmitoyl‐CoA as the substrates, the complete kinetic characterization of CPT I in fish has been described, which increases our knowledge about lipid metabolism and its critical role in lipid utilization in fish.  相似文献   

19.
To investigate the effects of high level of lupin meal (LM) supplemented with organic selenium (OS) on the growth and blood biochemistry of barramundi (Lates calcarifer), four isocaloric and isonitrogenous diets were prepared, containing either non‐fermented or fermented LM, and either supplemented with 2 mg OS/kg (LM, LMOS, FLM and FLMOS), or not. A fishmeal (FM)‐based diet formulated for juvenile barramundi was used as a control diet. Fish (initial mean weight of 5.88 g) were triplicated and fed the test diets for 75 days. The findings demonstrated that growth performance of fish fed with the FLM and FLMOS diets were similar to fish fed with the FM diet (p > .05). The antioxidant glutathione peroxidase (GPx) activity, and haemoglobin (Hb) of fish fed with the FLMOS diet were significantly higher than that of FM‐fed fish (p < .05). Plasma alanine aminotransferase (ALT) activity was significantly increased in fish fed with non‐fermented diets (LM and LMOS) than in those fed with fermented LM diets (FLM and FLMOS) (p < .05). However, there were no significant differences in ALT activity among LMOS, FLM, FLMOS and FM diets. There was an interaction between the LM and OS on plasma CK activity; the CK of fish fed with diets supplemented with OS was higher in non‐fermented LM diets but lower in fermented LM diets (p < .05). This study suggests that fermented LM have an obvious potential to substantially replace 75% FM protein in the diets of barramundi.  相似文献   

20.
The present study investigated the antifungal effects of essential oils of oregano (Origanum onites) and laurel (Laurus nobilis) on Saprolegniasis, a disease that occurs in rainbow trout eggs during the incubation period. Oregano and laurel were ground after drying, and essential oils were obtained by water distillation method using a Clevenger apparatus. The essential oils were added to potato dextrose agar (PDA) at the rates of 1–1000 ppm, and the minimum inhibitory concentration (MIC) was determined as 250 ppm whereas the minimum lethal concentration (MLC) was determined to be 500 ppm for both plants. In the in vivo trials, fertilized eggs were treated with predetermined doses either by bathing during water hardening and incubation period or only during incubation period, and death rates were monitored during embryological development. The best larvae hatching rate was determined in 500 ppm oregano and 500 ppm laurel groups treated during water hardening plus daily as 82.11% and 79.87%, respectively. According to the results, it was determined that oregano and laurel essential oils exhibited better results in all doses compared with the negative control group, and 500 ppm dose had a better effect than the positive control group treated with formalin.  相似文献   

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