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The main objective of this study was to evaluate some health indices in rainbow trout (O. mykiss) broodstock via enhancing their food quality by adding two sources of astaxanthin (synthetic and algae) in feed.. 7 groups consisting of 6 treatments of two different astaxanthin levels and sources and a control (without astaxanthin) were considered. So, algal astaxanthin (Haematococcus pluvialis) in the three levels of 2.67, 3.55 and 8 gr/kg food (T1,T2, T3) and synthetic source in three levels of 40, 80 and 120mg/kg food in diet (T4, T5, T6) were examined on trout broods (3-4 years) for 120 days before the spawning season. Significant difference was observed among the treatments in terms of health-related blood factors. The broods which were fed with algal astaxanthin had lower blood sugar. Changes in albumin revealed that with the increase in astaxanthin the albumin level was increased first and then decreased. While the change in serum globulin treatments containing synthetic astaxanthin was not regular, it was so in algal astaxanthin. Overall, the results asserted that the application of astaxanthin improves health indices of rainbow trout broodstock. It also concluded that algal astaxanthin (Haematococcus pluvialis) for the reason that it contains supplementary nutritious, is extraordinary preferable than synthetic astaxanthin to improve health indices of rainbow trout broodstock.

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The presence of nanoparticles affects the physiological condition of fish and reduces the immune function of fish, so the use of immune stimulants such as molasses is very important. 250 juveniles of common carp for 42 days in four categories: ration without molasses (treatment 1), ration containing 0.5% molasses (treatment 2), ration containing 1% molasses (treatment 3) and ration containing 2% molasses (Treatment 4) were divided. Then, 50% of the lethal concentration of nano-iron was added to each group for fourteen days. Histological studies of fish exposed to molasses and iron nanoparticles showed structural abnormalities in liver tissue. So that these changes were very different compared to the tissues of the control group. The final conclusion of the present study showed that nano-iron treatment led to tissue damage in carp liver; Although histopathological complication was also observed in the combination of nano-iron and molasses treatments, but the severity of injuries decreased with increasing molasses concentration. The negative effect of iron nanoparticles on normal carp liver tissue by molasses seems to be minimized.

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Although the use of indicator organisms and their different tissues is commonly used to evaluate environmental pollution, there is still a need to identify a non-lethal, reliable and sensitive indicator in aquatic environments. In this research, multivariate indices were used based on habitat accumulation conditions. For this purpose, the ratio of elements of pectoral fin spines of ozone-exposed fish were compared as a non-lethal index to evaluate the habitat of the north and south of the Caspian Sea. For this purpose, multivariate analyzes and non-normal analyzes were used in the required cases to compare the samples of North and South Caspian Sea. The ratios of W: Ca, Tl: Ca, Ta: Ca, Sn: Ca, Se: Ca, Ni: Ca, Nb: Ca were higher in the southern samples than in the northern ones, which probably reflected the difference in the availability of metal absorption compared to calcium. Despite the recorded differences in the proportion of pectoral fin spine elements of ozone-exposed fish between the north and south of the Caspian Sea, all the multivariate results also reflected this habitat differentiation. These results showed that the pectoral fin spine can be confirmed as a good non-lethal indicator due to its capacity to accumulate pollutants and also as a biological indicator, and therefore it can be used for environmental evaluations, although the importance of continuous monitoring and protective measures is suggested along with continuous evaluations.