Journal of Aquaculture Development
Year:2013 | Volume:7 | Issue:2|Papers Count:8

Iridoviruses having five genera of Iridovirus, Chloriridovirus, Ranavirus, Lymphocystivirus and Megalocytivirus cause disease in many marine and freshwater fishes. This virus has been identified in different sturgeon species such as White sturgeon (Acipenser transmontanus), Paddlefish (Polyodon spathaula), Russian sturgeon (Acipenser guldenstaedtii) and Pallid sturgeon (Scaphirhynchus albus).Considering the importance of sturgeon species in Caspian Sea, this study carried out for the first time on Persian sturgeon spawners caught in southern coasts of Caspian Sea. Since Iridovirus usually stay in epithelial cells of skin, especially in fins and reproduced quickly. We preserved 150 samples of pectoral fins in -20°c freezer for DNA extraction using IQ2000 identification kit. DNA extracted using produce as well as solutions provided by the sets of kit. The DNA quality was assessed using 1% agaroze gel electrophoresis PCR performed using suitable DNA and specific primers. In order to check the quality of PCR product 5ml of PCR product, electrophoresed by 2% agaroze gel and stained by Ethidium Bromide.Based on the sample presented on the kit, all the samples which have not carrying out Iridovirus, should produce 655 base pair PCR band and this band created in all samples. Therefore, according to results obtained in this investigation no Iridovirus has been detected in Persian sturgeon brood stocks.

Yersinia ruckeriis the etiological agent of enteric red mouth disease (ERM) or yersiniosis, a general septicemia affecting mainly Salmonids. This disease is common word wide and produced considerable economic losses in the fish farming industry. Therefore current identification of pathogen from fish is essential for the effective fish disease control. An epidemic of disease in rain bow trout was occurred in Tonekabon city in Iran. In this study as well as biochemical detection we confirmed that laboratory culture based method by alignment analysis from sequences that outcome of PCR that used by universal primers. In contrast to biochemical same study in Romania that had detected Yersiniaby using the API 20E gallery, numerical values corresponding to the each group have been changed from 5.104, 100 at Romania to 5, 105, 100. in Iran. this difference due to positive VP test in our study and negative VP test was carried out in Romania The high throughput and excision detection rDNA PCR- sequencing used by universal primers rather than conventional method in this study provide a powerful addition tool to conventional methods for more accurate detection and monitoring of yersinia ruckeri. This study reports the first biochemical identification of Yersinia ruckeri by API Gallery and its confirmation by rDNA- PCR-Sequencing at the country of Iran.

Rainbow trout (oncorhynchus mykiss) is the only species of Salmonidae that is cultured in cultivation farms in Iran. Amount of Rainbow trout production in Mazandaran Province is very much.Recently the rate of incidence of different diseases is increasing in rainbow trout farms. Therefore we surveyed some biochemical and serum factors of infected and disinfected rainbow trout by bacteria in 2008. Eighteen ponds of breeding and culture of rainbow trout have been selected for sampling and survive. First of all the fish’s biometry and blood sampling have been done. Then we have culture the kidney of them in the TSA and Blood Agar. The separated serum from the fish blood measuring by different factors like albumin, pure protein, C3, C4, IgM and different enzymes like SGOT and SGPT.Achieved conclusion shows that out of all the fishes samples 60.5% were positive and 39.5% were negative by bacterial culturing. Among the serum factors and biochemical factors, average amount of pure protein and SGOT in disinfected fishes were clearly more than infected fishes (p<0.05). Average of C4 and SGPT in disinfected fishes were more than infected fishes but statistically it wasn’t significant (p>0.05). Average of pure IgM and C3 in infected fishes with bacteria were more than disinfected fishes but this differences was meaningless (p>0.05).

The epizootic diseases could be considered as most important threats in hatchery and cultured Ornamental fish farms that may faced with mortality occurrence and economic lost. Viral Nervous Necrosis (VNN) was emerging disease and approved in Golden grey mullet of the Caspian Sea in recent years. Study on histopathology changes of some important ornamental fish such as Guppy, Zebra, Oscar and Gold fish to acute virus of VNN was main objective in this research that carried out in Virology Lab of Inland Water Aquaculture Institute in Aug.2010. So after adaptation period challenge affaires were done on them with supernatant of affected mullet fish with Bath challenge and Intravitreous injection in Guppy and zebra fish and I.P method in Oscar and Gold fish. Then all exposed fish were investigates and mortality cases and clinical signs were recorded daily. Suspected samples were taken from affected fish with abnormal swimming behavior, lethargy, exophthalmia and skin darkening and then delivered to laboratory for histopathology and Indirect Fluorescent Antibody Test (IFAT). In comparison of control group, some histopathological lesions such as edema, inflammation, hyperemia, necrosis and pyknotic in nuclear of cells and clear vacuolation were observed in brain tissue and less than in retina. Also, IFAT findings approved completely mentioned histopathology results. Therefore it could be concluded that mentioned ornamental fish species could be sensitive to acute virus of VNN.

In comprehensive hydrobiological and hydrological investigation conducted in Aras reservoir dam, investigating the status of plankton community as a basic study for enhancing fish production have been conducted. This study carried out during summer 2002 to spring 2003. Phytoplankton samples were collected by Nansen water sampler from 5 stations at surface, 5, 10, 15 meters of water column. Zooplankton samples were collected by Juday net sampler at the same stations and depths as phytoplankton. Samples were preserved with Formaldehyde at % 4 concentration for analyses in the laboratory. In the present phytoplankton study 4 phyla and 41 genera were identified. The maximum density of Phytoplankton belongs to Phylum Bacillariophyta with genera Cyclotella, Synedra, Nitzschia and Gomphonema. This Phylum observed mostly in Spring and had %75.8 total abundance in the year.Chloropyta were the second major phylum, with genera Chlamydomonas, Scenedesmus and Schroderiahad %19.4 total abundance, and Cyanophyta with Microcystis which observed mostly in summer, had %4.7 total abundance and Euglenophyta had a few percent of population in the year. The average of phytoplankton abundance was 1.1×1010 n/m3 belongs to Aras entrance. Zooplankton study revealed 4 phyla and 26 genera, maximum density of zooplankton belongs to the phylum Rotatoria with genera Keratella, Synchaeta and Polyarthera. This phylum was observed mostly during in Spring and had %76 zooplankton total abundance in the year. Arthropoda were the second major phylum, in class Copepoda with genera Cyclops and Diaptomus and their Nauplious were observed mostly during in summer, had %11.2 and their nauplious had %3.5 total abundance in the year. Other zooplankton group had a few abundance during the year. The average of zooplankton abundance was 895326 n/m3 which was similar to Phytoplankton abundance. The data analysis showed, planktons were concentrated in the surface layers of water column and their population decreased as depth increases.

Water quality of the Shahid Beheshti sturgeon hatchery was assessed simultaneously with the management of fish health and hygiene of this hatchery during three terms of sturgeon culture from 2006 through 2008. This study was conducted during different stages of breeding and rearing of sturgeon including incubation (hatching to pre-larva stage), vniro (larval stage), and earthen rearing ponds (larval to fingerling stage). Water temperature, dissolved oxygen concentrations (DO), pH, electrical conductivity (EC), total dissolved solids (TSS), nitrite (N-NO2-), ammonium (N-NH4+) and ortho phosphate (P-PO43-) were measured and recorded. Nitrite, nitrate, ortho phosphate, EC and total hardness of water in the vniro tanks were measured 3 days after hatching, before the onset of exogenous feeding and again 5 days after yolk sac absorption as well as in rearing ponds throughout the rearing period. In the first year, water temperature, DO and pH in earthen rearing ponds were measured on a daily basis throughout the culture period. Statistical analysis of results was conducted by SPSS software and Excel was used to plot graphs. During the study period water temperature varied from 14.7-23.7 ºC in the incubation stage and from 13.7-24.5 oC in the vniro tanks. Similarly DO concentrations varied from 6.49-9.86 mg/l and 4.48-8.5 mg/l in the incubation stage and vniro tanks, respectively. pH values recorded in the incubation stage varied from 7.0-8.48 and from 7.3-8.1 in the vniro tanks. Nitrite levels were below the acceptable levels (<0.1 mg/l) for fingerling culture, whereas concentrations of ammonium measured in some samples of the earthen ponds were above the acceptable levels (0.015 mg/l) for this factor. No significant effects (P>0.05) of variations in nitrite and ammonium levels in the water were observed on survival rate of fingerlings in rearing ponds. DO concentrations in rearing ponds significantly affected (P<0.05, r=0.97) survival rate of fingerlings. The results of this study demonstrate that decrease in dissolved oxygen concentrations resulted in decrease in resistance of sturgeon fingerlings, making them vulnerable to pathogenic factors.

A 60-day feeding trial was conducted to examine the effect of dietary mannan oligosaccharide (MOS; activeMOS) on growth, survival and body composition in Rainbow trout juvenile (Oncorhynchus mykiss) with initially average weight 1.67±0.006 g. Basal diet were supplemented with 0 (control), 1, 2.5 and 4.0 g/kg MOS in a totally randomized design trial with three replicate. The experiment carried out in 200 L tanks. Result showed that in level of 1 g/kg MOS acquired body weight, total length, growth rate and conditioning factor was significantly higher than the other experimental group (P<0.01).The highest of carcass protein and lipid was obtained in 4.0 g/kg MOS and control group respectively (P<0.05).The group tested with 1 g/kg MOS had higher intestinal lactic acid bacterial count (P>0.05).There were no significant difference in survival rate between treatment (P>0.05).The result indicated that 1 g/kg MOS could improve growth and feeding efficiency in rainbow trout juveniles and this kind of prebiotic could be an appropriate complement in diet cultured rainbow trout.

Nowadays, the effect of pollutants on the process of embryonic development and especially aquaculture has been proved. The purpose of this study was to survey the effect of toxicity of mercuric chloride on the process of white fish genesis. This research was done thorough 2 stages in Shahid Rajaii Center of White Fish Proliferation in 1390. The first stage was done within 96 hours. In order to determine the toxicity of mercury chloride, the experimental group was treated 3 times with a concentration of 20, 50, 100, 150 and 200 ppb, while the control group was treated as many times as the experimental group with no mercury chloride. The result showed that the amount of LC50 96h on embryos of white fish was 102.91 ppb. The second stage was done during seven days to find out the effect of mercury chloride on organogenesis stage of embryos through 3 treatments with a concentration of 20, 50 and 100 ppb, which is lower than LC50. Having considered the embryonic stages and statistical analysis in the 20-ppb treatment, the researcher found that mercuric chloride solution in water caused a delay in the development, growth reduction, 6.23 percent of mortality rate and 3 to 7.5 percent organ abnormality including curvature in tail area and spine among embryos.Meanwhile, with the treatment of 50 and 100 ppb, we witnessed an increase of 30.25 and 49.5 percent in the mortality rate respectfully. An abnormality rate of 30.9 percent was also found in 50-ppb treatment and an abnormality of 53.9 percent in the treatment of 100 ppb.