Characterisation of Pigment Producing Bacteria Isolated from Bio Floc Ponds and Its Colour Enhancement Effect in Xiphophorus helleri

Abstract

Background: Biofloc technology is a minimal or zero water exchange technology which exerts beneficial effects on water quality, improves feed conversion ratio by recycling microbial protein in the culture of commercially important finfishes and shellfishes. This culture technique also improves the pigmentation in the ornamental fish culture. The presence of pigment producing bacteria and the absorption of the pigments by the ornamental fishes under biofloc technology would pave a long way to boost the production and export market of the high value fishes. Therefore, the present study evaluated the use of bacterial pigments isolated from the biofloc culture in the diets of Swordtail ornamental fish for its colouration and pigment absorption ability. Methods: A 30 days trial was conducted to evaluate the colour enhancement in swordtail through the supplementation of pigment produced from the bacteria in their diets. Swordtail fishes (1.2±0.01 g) were stocked in 100 litres tanks (20 nos/tank) in triplicates. Fish fed with normal diet served as control and diet supplemented with pigment (50 mg/kg) isolated from the bacteria Exiguobacterium profundum (T1), Chryseobacterium joostei (T2), Staphylococcus pasteuri (T3), Staphylococcus arlettae (T4) served as treatments. The characteristic features of the pigments isolated from the four different bacteria were checked and showed enhanced antibacterial, total antioxidant activity and the reductive ability. Result: Significant difference was observed in water quality parameters except temperature between the experimental groups. Growth parameters showed significant difference between control and treatment. Highest carotenoid concentration was found in fishes fed with pigments extracted from Staphylococcus pasteuri compared to other experimental groups. The present study proved the incorporation of bacterial pigments in the diets of Swordtail enhanced the total carotenoid concentration.