Prevalence of Ectoparasitic Infection and Its Impact on Haematological Parameters of Labeo rohita (Rohu) in Selected Freshwater Ecosystems of Nanded District, Maharashtra

The present study demonstrated the occurrence of ectoparasitic infection and associated haematological alterations in Labeo rohita collected from selected freshwater ecosystems of Nanded District, Maharashtra. Among the 120 fish examined, 46 were infected, giving an overall ectoparasitic prevalence of 38.33%. A total of 199 ectoparasites were recovered, resulting in a mean intensity of 4.33 parasites per infected fish. The highest prevalence was recorded at Godavari River at Raher (S3; 47.50%), followed by Godavari River near Nanded (S2; 37.50%) and Vishnupuri Dam (S1; 30.00%). Argulus sp. was the most abundant ectoparasite, followed by Trichodina sp., Dactylogyrus sp. and Ichthyophthirius sp. Infected fish showed reductions in Hb, RBC, PCV, MCV, MCH and MCHC, whereas WBC, lymphocytes, neutrophils, monocytes and basophils increased. These findings indicated an association between ectoparasitic infection, erythrocytic disturbance and an enhanced leukocytic response. The study demonstrated that combined parasitological and haematological assessment can provide useful baseline information for evaluating freshwater fish health in the selected ecosystems of Nanded District. Regular monitoring of ectoparasites and physiological indicators may assist in the early detection of health deterioration in freshwater fish populations. Future investigations incorporating seasonal variation, water-quality parameters, histopathology, parasite intensity and molecular identification of parasites are recommended to further clarify host–parasite and environmental relationships in L. rohita.

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