The present study aimed to elucidate the impacts of dietary vegetable oil blends as alternative to fish oil on serum biochemical and haematological parameters in Heterobranchus longifilis fingerlings. Fish (4.65 ± 0.23g) were fed diets containing fish oil (FO), palm oil (PO), soybean oil (SO), blend of PO and SO (POSO) over a 12-week period. The experiment was carried out in 62-l circular tanks with 10 fish per tank. Fish were fed two times a day until apparent satiation. At the end of the experiment, blood samples were collected from each treatment for investigation of serum biochemical and haematological parameters. The results showed that total protein was not significantly affected by the different dietary lipid sources (p >0.05). However, serum glucose was significantly higher in fish fed the control diet (p<0.05). Activities of liver enzymes (AST, ALT, ALP), total cholesterol, triglyceride, LDL and HDL exhibited a significant increase in the blood of fish fed combinations of the vegetable lipid sources (p<0.05). The PCV, RBC and MCV were not affected by the dietary lipid sources (p>0.05). These results indicate that FO can be replaced with PO, SO or their combinations in the diet of H. longifilis fingerlings without any negative health impacts.