Effect of different levels of sub-lethal concentration (LC5096h) of heavy metal zinc on growth, survival and some hematological parameters in rainbow trout (Oncorhynchus mykiss) fingerling

Document Type : Research Paper

Authors

1 Associate Professor in Aquatics and Fisheries Department, Mirzakochek Khan Fisheries Science Education Unit, Guilan Research Center, Agricultural Research, Education and Extension Organization (AREEO), Rasht, Iran

2 M.Sc. Student in Biophysics, Department of Biology, Kharazmi University, Karaj, Iran

3 Assistant Professor in Aquatics and Fisheries Department, Mirzakochek Khan Fisheries Science Education Unit, Guilan Research Center, Agricultural Research, Education and Extension Organization (AREEO), Rasht, Iran

10.22124/japb.2025.29778.1562

Abstract

This study was conducted to evaluate the effect of heavy metal zinc on growth, nutrition, survival rate and some blood indices of rainbow trout (Oncorhynchus mykiss) fingerlings. A total of 540 fish (20.19±2.45g) were divided into four treatments and three replicates (45 fish per replicate). Treatments 1 to 4 were reared with identical diets and water containing 0, 5, 25 and 50% of LC5096h concentration (9.4mg/L) of zinc for 8 weeks, respectively. The results showed that adding zinc to water had a significant effect on reducing the survival rate of fingerlings (P<0.05). The number of red blood cells in the experimental treatments of 25 and 50% of zinc concentration decreased compared to the treatment of 0% (P>0.05). White blood cells in the experimental treatments of 25 and 50% zinc concentration showed a significant decrease compared to the 0% treatment (P<0.05). In the 5% treatment, red and white blood cells increased compared to the other treatments (P<0.05). Zinc had a positive effect on growth variables and blood indices in the 5% treatment. There was a significant difference between the 25 and 50% treatments in growth variables and the number of red blood cells, hematocrit, hemoglobin and red blood cell indices with the 0 and 5% treatments (P<0.05). In general, exposure of rainbow trout fingerlings to zinc at a level above 5% LC5096h caused changes in the amount of blood indices, growth and survival rate of this fish. Therefore, monitoring water quality in terms of zinc pollution is essential for the economic and hygienic production of this fish.

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Aquatic Physiology and Biotechnology
Volume 13, Issue 3
January 2026
Pages 59-79

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