In the present work an attempt has been made to study the effect of exogenous hormonal treatment on changes in haematological indices in a fresh water mud eel teleostean fish, Macrognathus aculeatus (Bloch). The treatment of T , T Methyl-testosterone, Hydrocortisone, ACTH, Adrenaline, Phentolamine 4 3, and Growth hormone (GH) brought significant (P<0.05) increase in TEC counts, Hb, PCV and oxygen carrying capacity, as compared to control group. The MCV, MCHC and SAE showed decreasing trend. Thiouracil failed to alter changes in these parameters to a significant level. The details have been discussed in this paper.