Remarkably high survival rates under dim light conditions in sutchi catfish Pangasianodon hypophthalmus larvae

Abstract

The sutchi catfish Pangasianodon hypophthalmus is an important species for aquaculture in Southeast Asia. However, larvae typically have low survival rates due to their predilection for cannibalism during rearing. This study investigated larval feeding behavior and rearing conditions. The former experiments were performed to elucidate the role of sensory organs in feeding, and the latter experiments examined the effect of dim light on larval rearing and survival rates. Neither lighting conditions (light and dark) nor blocking of free neuromasts by streptomycin had significant effects on feeding behavior. Therefore, the feeding behavior of sutchi catfish larvae most likely depends on chemosensing rather than visual sensing. In the later experiments, larval rearing at 0.1 l9 yielded significantly higher survival rates than other lighting conditions (0.00, 1, 10, 100 l9). Survival in the 0.1 l9 group was almost three times higher than in the 100 l9 group. Moreover, larvae reared under 0.1 l9 showed steady growth. Therefore, it is concluded that 0.1 l9 is the optimum light intensity for sutchi catfish larval rearing.

Why is cannibalism less frequent when larvae of sutchi catfishPangasianodon hypophthalmusare reared under dim light?

“…Feeding behaviour of fish larvae is closely related to their sensory organs (Blaxter ; Mukai & Kobayashi , ; Fuiman, Higgs & Poling ; Mukai , ; Mukai, Lang, Sitti Raehanah & Senoo ; Mukai, Tuzan, Lim et al . ).…”

“…). Moreover, Mukai () also reported that sutchi catfish show survival rates three times higher under dim conditions (0.1 lx) than those under brighter conditions (100 lx). Mukai () postulated that this was a result of the less aggressive behaviour of catfish under dim conditions; however, there is no quantitative data to support this claim.…”

“…Sutchi catfish larvae can be reared under dim light or darkness (Mukai ,b). They can also eat food under dark conditions, which implies that their feeding behaviour must be dependent on sensory organs other than eyes.…”

Comparison on growth performance, body coloration changes and stress response of juvenile river catfish, Pangasius hypophthalmus reared in different tank background colour

“…Cannibalism can cause heavy losses during the early stages of cultured fish especially river catfish. The growth performance of river catfish has been manipulated by feeding frequency, stocking density and light intensity (Mukai, ; Sayeed, Hossain, Mistry, & Huq, ; Slembrouck, Baras, Subagja, Hung, & Legendre, ). The present was conducted to identify the most ideal tank background colour to further enhance the growth performance, suppress cannibalism and perhaps increase the value of seed of river catfish.…”

Visual thresholds for feeding and optimum light intensity for larval rearing of Asian seabass,Lates calcarifer(Bloch)

“…It is important to understand the visual sensitivity and behaviour of fish larvae in their natural habitats, and to determine the optimum illuminating conditions in captivity. There are many studies on visual sensitivity of fish larvae through retinomotor responses (Ali ; Blaxter ; Blaxter ; Blaxter & Staines ; Kawamura ; Neave ; Masuma, Kawamura, Tezuka, Koiso & Namba ) and on feeding behaviour under different light intensities (Blaxter ,b; Mukai , ; Mukai, Tuzan, Lim & Yahaya ). Boeuf and Bail () describe the effect of light intensities on growth of many fish species.…”