---

This study was conducted to compare heavy metal concentrations including lead and cadmium in liver and muscle tissues of Indian mackerel (Rastrelliiger Kanagurta) in Bandar Lengeh, Hormoz island, Hengam island and Kolahi regions. In current research, the influence of season, sex and size (length and weight) on Pb and Cd concentrations in Indian mackerel was investigated in these areas. Then Lead and cadmium concentrations in muscle tissues were compared with international standards for human consumption. Sampling was performed in summer and winter. Metal concentrations of organs were assessed by dry digestion method and atomic absorption spectrometer (AAS). Results showed that there are statistically significant differences between concentrations of lead and cadmium in liver and tissues of the fish in these regions (Bandar Lengeh, Hormoz, Hengam and Kolahi) (p<0.05), also concentrations of lead and cadmium have significant differences in summer and winter (p<0.05). The comparison of results of heavy metal concentrations with international standards including NHMRC, MAFF and WHO demonstrated that the amount of lead and cadmium is lower than allowable limits and doesn't have any problem for human consumption. Concentrations of Pb and Cd in both sexes of Indian mackerel have no significant differences (p>0.05). In addition, there is no correlation between lead and cadmium concentrations in muscle and liver of Indian mackerel with size (length and weight) (p>0.05).

---

According to the importance and position of fish for human protein supply, studying pathogens and more familiarity with their parasitic diseases can be a step towards improving the knowledge of parasitology in the country. The aim of this study was to identify the metazoan parasites of the Indian mackerel (Rastrelliger kanagurta) caught from the coasts of the Oman Sea in the Chabahar region. In the present study, 61 pieces of R. kanagurta were caught in summer 2019. The fish were transported to the laboratory and their length and weight were measured. Different organs of the fish such as gills, eyes, stomach, pyloric caeca, gonads, and intestines were examined for isolated parasites were stabilized in alcohol 70% and/or formalin 10%. The identified parasites were from the digene category and including Lecithocladium angustiovum and prodistomum orientale with frequency of 100% and 26.4%, respectively, from the category of monogenic parasites, Indomazocraes sp. And another example of the family Mazocraeidae, both with prevalence of 1.9% and from the nematode genus, the larvae of the parasite Anisakis sp. were identified with a prevalence of 1.9%.The results showed that the digenean parasite Lecithocladium angustiovum had the highest severity of infection in the stomach (16.1±17.3). In this study, according to the results, the identified parasites included two digens at the genus and species levels, a monogenean at the genus level and another in the family of flatworm branches, a nematode at the genus level in roundworm branch. This is the first report of the Indian mackerel parasites from the Oman Sea coast. Also, the parasites of Prodistomum orientale, Indomazocraes sp. and a specimen belonging to the family Mazocraeidae are reported for the first time of this fish from the coasts of Iran.