BACKGROUND: Application of green chemistry to the synthesis of nanomaterials is of vital importance in medicinal and technological aspects. Recently, synthesis of silver nanoparticles using plants and marine macro algae to adapt this approach to the environment, has become  more popular. Objectives: The purpose of this study is biological synthesis of silver nanoparticles using seaweed, Sargassum angustifolium, and determining its toxicity in common carp. Methods: First, synthesis of silver nanoparticles using Sargassum algae was conducted and then acute toxicity of these silver nanoparticles was investigated at static renewal condition during 96 hours in common carp according to standard methods (1998) OECD. Results: TEM analysis showed that the average size of the bionanoparticles was found to be 32.54 nm and spherical in shape. The toxicity results showed that the LC50 at 24, 48, 72 and 96-h after exposure was 79.54 ± 0.007, 52.17 ± 0.006, 30.62 ± 0.008 and 11.34 ± 0.016 mg/l respectively. Conclusions: Analysis related to the characterization of the properties of silver nanoparticles proves bioreduction of silver ions by sargassum seaweed extract. According to the results the mortality rates of common carp showed an increasing trend with increasing concentration and exposure time, which indicates the toxicity of this substance in high concentration for common carp.

BACKGROUND: Vitamins are considered an essential part in diet of aquatic animals. OBJECTIVES: This study was carried out to assay the effect of different levels of vitamin E on growth performance, carcass compositions and blood parameters of common carp fingerlings (Cyprinus carpio). METHODS: Total number of 96 common carp fingerlings weighing 15.49 ± 3.64 g were randomly distributed into 12 fiberglass tanks in four treatments group including control (without added vitamin), 100, 200 and 400 mg/kg vitamin E in three replicates and kept at a density of 8 fish per tank for 10 weeks. RESULTS: Results showed that the highest weight gain, percentage of body weight increase, mean daily growth, specific growth rate, condition factor and the lowest food conversation ratio were observed in fish fed with 200mg/kg vitamin E but no significant differences were seen compared to other treatments (p>0.05). Fish fed with 200mg/kg vitamin E had the highest (p>0.05) contents of protein and ash compared to control group. There was an increase in values of RBC, Hct and Hb in fish fed with 100, 200 and 400 mg/kg vitamin E in comparison with control group. Significant differences were observed in MCHC in fish fed with 100 mg/kg vitamin E compared to control and fish fed with 400 mg/kg, also treatment 200 mg/kg with treatment 400 mg/kg vitamin E (p<0.05). Fish fed vitamin E in 200 and 100 mg/kg had the highest WBC count. Fish fed with different levels of vitamin E had higher lymphocyte in comparison with control group and fish fed with 100 mg/kg had significant difference with control in lymphocyte (p<0.05). CONCLUSIONS: Vitamin E in level of 200 mg/kg can play an important role to enhance growth performance, nutrition efficiency and improving blood indices and support cell immunity in common carp fingerlings.

BACKGROUND: Biofloc technology is considered  a method that degrades organic waste by microorganisms and produces bacterial flocculation. OBJECTIVES: This study was performed to evaluate of the application of biofloc technology in therearing of common carp (Cyprinus carpio) fingerlings in intensive culture. METHODS: The experiment was designed in four treatments (Commercial diet as a control, 75% commercial diet + Biofloc, 50% commercial diet + Biofloc, 25% commercial diet + Biofloc) with carp fingerlings (Initial weight 58 ± .2 g) over a period of one month. Water exchange in Biofloc treatments was 1% during 24 h while water flow through system was used in control. At the end of experiment, all fish were intraperitoneally injected with 12×107 colony forming units (CFU) of Aeromonas hydrophila per fish. RESULTS:The results of the experiment indicated that the highest weight gain was observed in fingerlings fed 75% commercial diet + Biofloc that differed significantly from the group fed 25% commercial diet + Biofloc (p<0.05). There was no significant difference between control and 50% and 75% commercial diet as well (p<0.05). No significant difference was observed in case of condition factor, viscerosomatic index (VSI) and survival in experimental treatments (p>0.05). Also, Biofloc significantly increased ash content in muscle (p<0.05). The highest mortality (64.2 %) was observed in control inchallenge of Aeromonas hydrophila. CONCLUSIONS: The results suggest that the Biofloc technology can increase growth performances of carp fingerlings in intensive system and decrease water exchange via quality improvement.