Iron supplementation in aquaculture wastewater and its impact on osmoregulatory, haematological, blood biochemical, and stress responses of pangasius with spinach in nutrient film technique based aquaponics

Abstract

A-105 day experiment was conducted to investigate the impact of various dosages of iron on osmoregulatory, haematological, blood biochemical, and stress responses of pangasius (Pangasianodon hypophthalmus) with spinach (Spinacia oleracea L.) using aquaculture wastewater in nutrient film technique based aquaponics. A Nutrient Film Technique based aquaponics unit was installed having a fish-to-plant component ratio of 2.8 kg/m3: 28 plants/m2 in all treatments. The parameters related to osmoregulatory, haematological, blood biochemical and stress of pangasius were evaluated at four various iron dosages, viz., T1 (1.0 mg/L), T2 (1.5 mg/L), T3 (2.0 mg/L), and T4 (2.5 mg/L) and equated with C (control) to observe the iron to be applied to an aquaponic system. Iron supplementation was found to have no negative effects on the quality of water. The fish production and yield of spinach were significantly (P < 0.05) higher after the iron supplement while the maximum growth and yield recorded were in the T2 treatment. The treatments T3 and T4 registered lower fish production and spinach yield as compared to T2 due to excess iron dosages. The parameters related to osmoregulatory varied insignificantly (P > 0.05) except for higher plasma iron concentrations, particularly in T3 and T4. Haematological parameters increased dose-wise. Total plasma protein and globulin were significantly higher in T4, followed by T3. A reduction in superoxide dismutase and catalase was observed. Based on the outcomes of this study, an iron dosage of 1.5 mg/L could be recommended as the optimal dose for pangasius-spinach aquaponics without compromising pangasius health.