Influence of rearing tank colour on Asian catfish, magur (Clarias magur) and pangas (Pangasius pangasius) larval growth and survival

Larval growth and survival are significantly influenced by the various biotic and abiotic factors. Rearing tank background colour is one such factor affecting the larval production in finfish hatcheries. The present study evaluated the effect of five tank background colours (black, white, blue, green and red) on growth and survival of larvae of two commercially important freshwater catfish species, Clarias magur (magur) and Pangasius pangasius (pangas) in a completely randomized experimental design in triplicate. The larvae of magur (9.33 +/- 0.15 mm; 3.85 +/- 0.05 mg) and pangas (10.07 +/- 0.27 mm; 3.31 +/- 0.08 mg) were stocked at a density of 45 and 30 larvae per tank, respectively in 15 L tanks. Experimental duration was 28 days for both the species. The results revealed that the final weight, weight gain, daily weight gain, and specific growth rate (SGR) of larvae of magur were significantly (P < 0.05) higher in white background coloured tank whereas, pangas shown the best performance (P < 0.05) in black tank. Thermal growth coefficient (TGC) of magur and pangas were recorded significantly higher in white and black coloured tank, respectively. Larval survival was significantly (P < 0.05) higher in black (97.04 +/- 1.96%; F-(4,F- 10) = 2.95, P = 0.002) tank for magur and green tank (87.78 +/- 4.84%; F ((4, 10)) = 8.28, P = 0.003) for pangas. Whereas green and black tank colour were significantly reduced the larval survival of magur and pangas, respectively. This study clearly indicates that tank background colour had a significant impact on the larval growth and survival in both the species studied. It was also noticed that the tank colour effect is species specific. The study thus showed that black background tank colour for magur and green tank for pangas are more suitable for the higher production of catfish larvae in hatchery.