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Aims: The present study intends to assess the toxicity of CuO and ZnO nanoparticles (NPs) at laboratory conditions on some pathogenic bacteria for the reared fish, as well as, a bioassay on rainbow trout.
Material & Methods: For this purpose, the sensitivity of them to the mentioned NPs with a reference antibiotic (florfenicol) was assayed through the well diffusion method, as well as, minimum inhibitory concentration (MIC) and minimum bacteriocidal concentration (MBC) were determined by microdilution technique. On the other hand, the lethal toxicity test has been accomplished to the calculation of median lethal concentration (LC50) on some rainbow trout (55.3±7.6 g) in static condition for the 96 consecutive hours. We use one-way ANOVA and Probit regression in order to data analysis.
Findings: Results show that NPs of copper oxide and zinc oxide could significantly inhibit the growth of Streptococcus iniae or kill it at 0.18 and 0.24 µg/ml and more, respectively. The comparison between LC50-96h quantities of CuO NP (107.4 µg/l) and ZnO NP (102.3 µg/l) indicated that the CuO NP has more toxic potential.
Conclusion: According to the laboratory findings, the susceptibility of S. iniae and L. garvieae to ZnO NP were close to florfenicol. The mortality in the fish species due to lethal toxicity would occur if the effective concentration of NPs on the bacterial pathogenic agents being used directly.

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Oil pollution of waters, in addition to disrupting the physiological function of fish, leads to irreparable damage to human health during transmission through the food chain. Therefore, the possibility of accumulation of petroleum hydrocarbons in the edible tissues of fish is of particular importance. In this study, samples of yellowfin seabream (Acanthopagrus latus; Houttuyn, 1782) were collected from the Khowr-e Musa area in the Persian Gulf using bait traps. after twenty days of adaptation to the laboratory conditions (South of Iran Aquaculture Research Center), the fishes was divided into five groups with two replications in tanks containing 300 liters of seawater. The groups were then exposed to concentrations of 0, 2, 4, 8 and 16% water associated fraction (WSF).
The results of the study of the amount of total petroleum hydrocarbons in the gills and kidney tissue showed a significant increase on days 10 and 20 of the experiment, which increased slightly with increasing WSF concentration (P <0.05). While liver and muscle tissue, considering exposure time and WSF concentration, no significant difference was observed (P> 0.05). The results of the present study showed the possibility of accumulation of TPH in the gill and kidneys of yellowfin seabream, under the influence of concentration and duration of exposure to WSF. Therefore, considering the high economic value of the Sparidae family, it seems necessary to provide appropriate management methods to control oil pollution in the Persian Gulf.

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Aeromonas hydrophila is an opportunist pathogen in fish and responsible for wide range of fish diseases. In this study, the effect of different levels of curcumin in the diet on growth and resistance to infection with Aeromonas hydrophila in common carp (Cyprinus carpio) was investigated by peritoneal injection. For this purpose, six concentrations of 0.2, 0.4, 0.6, 0.8 and 1% of different levels of curcumin were mixed with a special feed for carp. 360 common carp with an average weight of 50±4/7 g (divided into six groups), each group was divided into 60 fish and 20 fish per replication. Live Aeromonas hydrophila was exposed to concentrations containing Cfu/ml10 of Aeromonas hydrophila for 10 days and post-challenge mortality was compared between treatments.The results showed that administration of 0.8 and 1% curcumin caused a significant increase In the reduction of losses after challenge with Aeromonas hydrophilis in bacteria in treatments of 0.8 and 1% curcumin showed significant compared to the control treatment (p <0.05).In general, it can be said that the most appropriate concentration of curcumin in feed to increase resistance to infection Bacterial cells are 0.8 and 1%.

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In this study, the effectiveness of 4 killed VNN vaccines along with three types of adjuvants was evaluated by both immersion and injection methods. About 540 fish weighing 7-10 g of ozone (Acipenser stellatus Pallas 1771) were considered. Vaccination was performed in two stages one month apart, and one month after the second recurrence, exposure to the acute live virus was performed. During this period, the mortality rate of immersion and injection groups was 12.9% and 19.8%, respectively, compared to 100% mortality in the control group. Blood sampling was performed to assess immune factors (superoxide dismutase, lysozyme) in four stages before the first vaccination in the adaptation period, after the first vaccination, after the second vaccination one month and after exposure to live virus Acute was performed to identify changes before and after exposure to the virus. The results of the present study showed that immunization vaccination in the vaccinated group with the vaccine containing IMS 1312 SEPPIC adjuvant significantly higher levels of superoxide dismutase 1745 IU / MI (p<0.05) and lysozyme 40.6 (p<0.05). Compared to other groups, which proves its better efficacy compared to other vaccines. Therefore, a vaccine killed with 75% IMS 1312 SEPPIC adjuvant can be recommended for vaccination against VNN.

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This study was conducted from April 2017 to June 2018 in a Trout aquaculture farm in Firoozkoh, Tehran province, to distinguish environmental and managerial risk factors affecting incidence of viral diseases in the fish farm under study. Averaged visit from fish farm was 2 times a month and all biosecurity measures were advised and applied during every visit. Some of the physico-chemical parameters were recorded daily. Samples from all cargoes of eyed-eggs imported from abroad and also from larvae after active swimming and absorption of yolk sac were taken for RT-PCR test. Virology, bacteriology, parasitology and mycology tests in the farm and authorized laboratory were done. Clinical observations, macroscopic and microscopic examinations, checking all the sanitarian and productional managerial factors, also checking all the physical and chemical factors affecting the outbreak of viral diseases were done. During clinical observation of fishes, these symptoms were observed; anorexia, gathering at the raceway’s side and outlet, cachexia, one and two side exophthalmia, melanosis, integument ulcers, hemorrhage in ventricular and ocular areas, petechia in ventricular area, fecal casts, high mortality and also presence of a large number of moribund fishes. The result of the laboratory examinations was IHN positive of Rainbow trout fries. This disease caused about 80% mortality of the fries produced from the imported eyed-eggs cargo. The other fatalities with different reasons were also recorded such as; the Lutra’s attack at nights, the farm’s personnel running amongst other farms and transferrin pathogens, the transportation vehicles not being proper disinfected while inter to and exit from the farm and the severe food intoxication of fries. Regarding the results of this study, instruction of scientific and practical models has presented to decrease the effect of environmental and managerial risk factors in the incidence of the disease.

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The accumulation of nanoparticles in the environment and aquatic ecosystems due to their wide application in industries, agriculture, medicine and pharmaceuticals has caused an increasing concern about the environment and increasing exposure to nanoparticles in ecosystems and humans. Iron oxide nanoparticles easily enter the bloodstream, accumulate in different tissues and cause damage to these tissues. Therefore, in this research, changes in the intestinal tissue of gray mullet fish (M. cephalus) and tissue accumulation in oral exposure to iron oxide nanoparticles were investigated.
110 pieces of young gray mullet after 2 weeks of adaptation were treated in four-time groups of 1, 7, 14 and 28 days, and one group was considered as a control. The mullet fish received iron oxide nanoparticles twice a day at the rate of 15 mg/kg attached to the food. The results showed that although the amount of tissue iron increased significantly only in the 28-day group, the consumption of iron oxide nanoparticles in almost all groups increases the tissue accumulation of iron in the intestine. The intestinal histological study showed changes such as the increase in the number and size of goblet cells, destruction of microvilli structure, bleeding and degrees of necrosis, and the intensity and extent of the changes in the intestinal tissue increased with increasing exposure time.
These observations showed that the consumption of iron oxide nanoparticles has a negative effect on intestinal function and causes iron accumulation and the occurrence of time-dependent injuries.

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Today, the continuous release of environmental pollutants into aquatic ecosystems has made these environments extremely vulnerable and turned them into a storage sites for these toxic substances, so it is necessary to investigate the effects of these pollutants on aquatic life. The present study was conducted with the aim of determining the toxicity of silver nitrate and observing the behavioral changes of Litopenaeus vannamei during its exposure. To determine the toxicity, the standard method of OECD was used. At first, the viability and survival of Litopenaeus vannamei were checked after two weeks of acclimatization to laboratory conditions, then by conducting preliminary tests, the actual lethality values ​​of silver nitrate were obtained. In order to determine the median lethal concentration, shrimps were exposed to concentrations of  0.025, 0.05, 0.1, 0.2, 0.4 and 0.8 mg/L of silver nitrate for 96 h and their mortality were recorded daily every 24 h. The LC₅₀, LOEC, NOEC and MATC were calculated based on shrimp mortality. During the viability and survival test, no mortality were observed up to 96 hours, and the survival rate of shrimps was 100%. The value of LC₅₀, NOEC, LOEC and MATC were determined as 0.084, 0.02, 0.025 and 0.0084 mg/liter, respectively. In different concentrations of silver nitrate, shrimps showed behaviors such as abnormal swimming, fast movements of swimming legs, coming to the surface of the water, twisting the body around itself and eventually losing balance.

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In this study,the immunogenicity of streptococcosis/lactococcosis and yersiniosis vaccine in rainbow trout was investigated in farm.900 fish with an average of 50±5 g were divided into three treatments and three replications (injection treatment, immersion treatment and control group).Fish were kept for 60 days and samples were taken on the 30^th and 60^th days.Then the fishes were challenged for 14 days with three bacteria, Streptococcus iniae, Lactococcus garvieae, and Yersinia ruckeri.Sampling was done to evaluate lysozyme activity,complement, antibody titer and survival rate. The results indicated a significant increase in serum complement and lysozyme activity on the 30^th and 60^th days of sampling in the vaccinated groups compared to the control group (P<0.05).Antibody titers against S. iniae, L. garvieae and Y. ruckeri on the 30^th and 60^th days of sampling in the vaccinated groups had a significant increase compared to the control group (P < 0.05).The  relative percentage survival after 14 days of challenge with S. iniae, L. garvieae and Y. ruckeri in the injected group was (70, 60, and 76.6%),respectively, which was significant compared to the control group (P<0.05).Also, the relative percentage survival in the immersion group with S. iniae, L. garvieae and Y. ruckeri was(30, 36.6 and 53.3%),respectively, which was significant only in the group immersed with S. iniae (P<0.05).In general,it can be concluded that the use of polyvalent vaccine by injection and immersion has significant effects on the immunity and survival rate of rainbow trout. However, the injection method is more effective and suitable than the immersion method.

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This study aimed to produce a smart infection warning film based on chitosan and gum arabic containing anthocyanin (0.5, 0.75, and 1 g) as a wound infection warning. Chitosan/gum film was prepared in a ratio of 1:2 with different doses of anthocyanin pigment (0.5, 0.75, and 1 g), and the control sample was considered without anthocyanin. The prepared film was evaluated on Pseudomonas and Mannitol salt agar media. To evaluate the functional properties of the prepared film, the amount of moisture, solubility, thickness, and water absorption of the treatments were measured. The lowest and highest film moisture content were in the control treatment, and the treatment contained 0.75% anthocyanins, respectively. As the percentage of anthocyanin increased, the thickness and solubility of the samples decreased significantly. Regarding the water absorption test, the highest amount was related to the treatment containing 1% anthocyanin, and the lowest amount belonged to the control treatment. To evaluate the effect of chitosan or gum film containing anthocyanin on the culture medium when the bacteria were well grown, chitosan or gum biofilms containing different concentrations of anthocyanin were cut to 1.1 cm and cut into It was placed on the culture medium for 60 minutes, and the color change of the films was checked with a colorimeter. The highest rate of color change of films in culture medium containing Pseudomonas aeruginosa was obtained in the treatment containing 0.5%; however, in the case of Pseudomonas aureus, the highest color change was observed in the treatment containing 1%. Finally, the best film in terms of physical characteristics is the 1% treatment, and in terms of color change in response to the growth of Pseudomonas, it is 0.5%, and for Staphylococcus aureus, it is 1%.

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Evaluation of the antimicrobial activity of bacteria in the aquaculture ecosystem is the first stage of probiotic bacteria screening studies. The aim of the present study was to isolate the intestinal bacteria of cultivated Vanammei shrimp with antimicrobial activity against pathogenic bacteria in vitro and in vivo. For this purpose, sampling of shrimp culture sites in South Tiab and North Tiab was done in 3 stages. The results of counting culturable bacteria using Zobell agar culture medium showed that in South Tiab site, the average number of bacteria in shrimp intestine samples was from 3.66 × 10⁶ CFU/gr in the first stage of sampling to 4.63 ×10⁶ CFU/gr in the third stage. With a similar trend, the changes of this amount in the North Tiab site fluctuated from 16.4 ×10⁶ CFU/gr to 16.16 ×10⁶ CFU/gr. Evaluation of the antimicrobial activity of the isolates using the agar diffusion method showed that 9, 6, 4 and 3 isolates respectively compared to V. alginolyticus, V. harveyi, V. parahaemolyticus and P. aeroginosa showed antimicrobial activity.