Non-specific immune responses of the Indian major carp Labeo rohita Hamilton to infestation by the freshwater fish louse Argulus siamensis (Wilson)

Abstract

The study was undertaken to evaluate the non-specific immune responses of the Indian major carp, Labeo rohita naturally
infested with different loads of the freshwater fish louse, Argulus siamensis. Results showed that glucose level and total
antiprotease activity of serum were significantly higher in fish with different degrees of lice infestation, compared to uninfested
control fish. Complement and α-2 macroglobulin activities were significantly (p<0.05) lower in lice-infested fish as compared
to uninfested control fish. No significant canges were noticed in the NBT assay, myeloperoxidase activity, lysozyme activity,
ceruloplasmin activity, haemolysin titre and packed cell volume recorded in the uninfested control fish and lice infested fish.
The total protein and haemagglutination titres were not significantly different in fish infested with moderate and high levels
of the lice as compared to uninfested control fish. However, a higher value of glucose level, NBT activity and total antiprotease
level were observed in lice-infested female fish compared to their respective control fish. The alternate complement activity
(ACH50) natural haemolysin and haemagglutination titres were significantly lower in lice-infested female fish as compared
to uninfested female fish. In lice-infested male fish ceruloplasmin level was lower and total protein was significantly higher
as compared to respective control fish. The present study also showed a positive correlation of blood glucose level, total
antiprotease, NBT and myeloperoxidase activities with the degrees of lice infestation. The results of the study indicate that
fish immune system particularly of female fish is significantly influenced by Argulus infestation.