Age and Sex Related Variations in Hematological Profile of Rainbow Trout (Oncorhynchus mykiss) from Kashmir Aquaculture Systems

Rainbow trout is an important aquaculture species in Himalayas mainly raised for food and sports, yet little is known about their hematological response based on age and sex. The fish hematology is a vital source to know the health status of the fish. The present investigation focused on the age and sex-related changes in the hematological profile of Rainbow trout, Oncorhynchus mykiss. Fish samples were collected from Laribal Trout Fish farm, Kashmir. Blood samples of 224 specimens of trout (both male and female) belonging to 4 age groups 1, 2, 3 & 4 (56 per age group) were collected. Opercular bones were used for estimation of age. Histological examinations were carried out for determination of sex. Estimation of various hematological parameters were carried out using appropriate procedures. The values of Hemoglobin (Hb), Hematocrit (Hct), Total Erythrocyte Count (TEC) were found to increase with increase in age. However, Total Leucocyte Count (TLC) was found to decrease with increase in age. Mean Corpuscular Volume (MCH), Mean Corpuscular Hemoglobin (MCH) and Mean Corpuscular Hemoglobin Concentration (MCHC) also showed variations with age. Males showed higher levels of Hb, Hct, TEC, MCV, MCH and MCHC than the females. Only TLC levels were found higher in females. These findings suggest that fish have different hematological profiles based on age and sex. Therefore, when analyzing the effects of management and environmental factors on Rainbow trout in terms of their hematological profiles, it is crucial to take species age and sex into account.