Effect of stocking density on growth, proximate composition, hematology, and histology of the striped dwarf catfish (Mystus vittatus) in a biofloc system

This study assessed the effects of stocking density on growth, proximate composition, hematological parameters, and histological features of striped dwarf catfish (Mystus vittatus) in a biofloc system. Four treatments were applied: three biofloc densities (BFT350: 350 fish/m³, BFT300: 300 fish/m³, BFT250: 250 fish/m³) and a clean-water system as the control (Control350: 350 fish/m³ without carbon). The experiment was conducted in twelve concrete tanks, each containing 1000 L of water. M. vittatus (0.91 ± 0.02 g) were stocked in all the treatments and fed a pelleted diet for 90 days. Results showed acceptable water quality across treatments. Growth performance, survival, and feed utilization improved as stocking density decreased in the biofloc treatments, with the BFT250 treatment showing the best overall performance. Hematological analysis showed higher RBC, HGB, and HCT in BFT250, with WBC levels similar across treatments. Proximate analysis indicated the highest moisture and protein content in BFT250, while fat content increased with stocking density. Histological analysis showed normal liver and intestinal structures across all treatments, though differences in intestinal villus morphology were noted among various densities. Of the tested densities, 250 fish m⁻³ demonstrated the best growth, survival, and physiological parameters in the biofloc system.