JOURNAL OF AQUACULTURE SCIENCES
Year:2018 | Volume:5 | Issue:7 |Papers Count:5

This study aimed to investigate the effects of water-born silver nanoparticles (AgNPs) on gill histopathological alternation of Parrot and the possible protective effects of diet enriched with astaxanthin alone or in combination with bile salt.200 Parrot fishes (average weight 25.5±6.2) were randomly distributed in three different groups: control (basic diet), astaxanthin alone (4g/kg) or in combination with bile salt (1200 mg/kg). The fish were fedfor 90 days and then subjected to AgNPs, 250 mg/L for 5 days. The silver bioaccumulation and gill histopathology analysis were done before and after exposure period. The results showed significant increase in silver concentration in the gill tissues of the control group after AgNPs exposure (P<0.05), while feeding fish on diet enriched with astaxanthin alone or in combination with bile salt did not show such elevation in silver concentration (P>0.05). After exposure to AgNPs, different gill histopathological alterations such as hyperplasia, hypertrophy, looping, necrosis and fusion were observed in fish from all treated groups, although the intensity of them were significantly lower in the groups of fish fed on astaxanthin alone or in combination with bile salt, comparison to the control group. In general, it can be concluded that diet enriched with astaxanthin alone or in combination with bile salt as antioxidant supplement can reduce the harmful effects of AgNPs on the gills.

In the present research, the effect of simultaneous use of irradiation, with edible coating of basil seed gum and extract of marjoram on microbial properties of Fringebarbell sturgeon fillet was studied. Treatments were 2% edible coating of basil seed gum, 2 and 4% marjoram extract and 3 and 4 kGy gamma rays. Treated samples were stored at 4ºC and evaluated periodically for microbial evaluation. The result showed that total viable counts (TVC) and psychrotrophic counts in treatments containing 3 and 4 kGy radiation (treatment 4 and 6) had a lower growth rate than other treatments. Pseudomonadaceae bacterial growth rate was also low. Bacterial studies of Enterobacteriaceae indicated that all fillets treated with gamma rays and the extract had no colonies of this type of bacteria until the 10th day of storage (P<0.05) and in treatment 4, growth rate was lower than the other treatments. In addition to gamma rays, marjoram extract was effective in reducing the microbial load of the fillets, as in the irradiated treatments containing the highest amount of extract (4%), the growth of all bacteria was slower than the other treatments. However, treatments 4 and 6 had better microbial quality. Thus, considering the results of the research, using 3 kGy dose with 4% of extract of marjoram can be effective in increasing the shelf life of the fish fillet.

The present research studied the effect of different levels of ethanolic extract of Vitex agnus-castus on reproductive performance of Xiphophorus helleri. Productive fish fed diets containing different levels of Vitex agnus-castus extract, 0 (control or treatment 1), 750 (treatment 2), 1000 (treatment 3) and 1250 (treatment 4) mg/kg diet for 2 months. Fish fed diet containing of 1250 mg of Vitex agnus-castus extract significantly showed higher final weight, final length, weight gain index, weight gain and specific growth rate in comparison with control group (P<0.05). The highest relative fecundity and gonadosomatic index were observed in treatment 3. The results also showed that the highest ratio of larvae to female was observed in treatment 4 (P<0.05). It can be concluded that using of 1250 mg Vitex agnus-castus per kilogram diet can improve the growth and reproductive performance of X. helleri.

The purpose of this study was to find the role of 17 beta-estradiol on metabolic parameters and steroid hormones of Litopenaeus vannamei hemolymph. Shrimp with an average weight of 40.18±2.46 g received 0, 20, 40 and 60 mg/kg levels (E0, E20, E40 and E60) in the diet for 25 days. After adaptation to the rearing conditions, 80 shrimps were placed in 4 treatments (each with 2 replications). The results showed no significant changes in the majority of the parameters analyzed, except for the Haemocyanin and protein in the plasma (P>0.05). The highest protein, cholesterol and glucose levels in E40 treatment were 7.22±0.30, 97.65±8.70 and 80.78±4.35 mg/dL, respectively. There was no significant difference in the amount of steroid hormones between treatments with other treatments (except E40 treatment) (P>0.05). Based on the results, it can be reported that adding 40 mg of hormone to broodstock commercial feed improves hormonal activities of L. vannamei.

The aim of this study was to investigate the effects of dietary vitamin C (ascorbic acid) on growth performances, digestive enzymes activity and blood stress factors in rainbow trout affected by the toxicity of malathion in water. In this experiment, the fish were subjected to 1/4 concentrations of Lc50 96h of malathion for 28 days and during this period, fish were fed with different levels of vitamin C (0, 300, 600 and 900 mg / kg of Feed). At the end of experiment, the results of the study of growth performances showed a significant increase (P<0.05) in weight gain (WG) and specific growth rate (SGR) of fish fed with the highest vitamin level (900 mg/kg diet). Food conversion ratio (FCR) in fish under the aforementioned treatment showed a significant decrease compared to other treatments. In the case of digestive enzymes activity, lipase enzyme activity increased significantly in treatments of 600 and 900 mg/kg vitamin C in diet respectively. However, the activity of other enzymes did not differ significantly in vitamin C different concentrations in the diet (P>0.05). Blood stress indices showed that glucose level was significantly higher in control treatment (0 m/kg) compared to other treatments and blood cortisol levels were significantly lower in the treatment of 900 mg/kg vitamin C in the diet. Finally, the results indicate that vitamin C as an anti-stress agent has been able to reduce stress in fish and improve the metabolic status and consequently the growth performance of rainbow trout.