A study was conducted to determine the suitable rearing technique for the endangered Mastacembelus armatus, also known as spiny eel, in captive conditions. Three different domestication methods were used: T₁ (control), T₂ (muddy bed) and T₃ (biofloc). A total of 90 adult M. armatus fish were obtained from the Narashunda River in the Kishorganj area of Bangladesh. After 90 days, all treatments showed a decrease in growth tendency, but T₃ recorded higher growth performance than the other two treatments. Moreover, gonadal development progress was higher in T₃, as indicated by the gonado-somatic index (GSI) and histology study. However, muddy bed conditions in T₂ led to fish disease infestation, which was observed through liver histology. Among several hematological parameters, glucose was significantly lower in T₂ than in the other two treatments, while cholesterol significantly decreased in both T₂ and T₃ compared to T₁. However, hemoglobin did not significantly vary among all treatments. Higher RBC and lower WBC values in T₃ also indicate comparatively suitable rearing conditions than the other treatments. In conclusion, the results of the study suggest that T₃ (biofloc) treatment can be a better option for M. armatus domestication. This method can be used by farmers and breeders to rear M. armatus in captive conditions, which can ultimately be helpful for the conservation of this species.