Larviculture of a carnivorous freshwater catfish, Lophiosilurus alexandri, screened by personality type

Considering that each personality type in animals presents distinct physiological and behavioural responses, this study evaluated the efficiency of the Novel Environment test to classify larvae of Lophiosilurus alexandri into bold and shy individuals, which were then investigated for growth, cannibalism and mortality in larviculture of pure and mixed groups. Larvae with an average weight of 24.0 ± 1.7 mg and length of 14.1 ± 0.4 mm, were subjected to a Novel Environment test to classify their personality type (bold and shy larvae). After the larvae were classified according to personality type, they were subjected to larviculture for 15 days. Three treatments were tested: only bold larvae, only shy larvae, and a mixed treatment (bold larvae + shy larvae) at a density for 16 larvae/L, which were fed 3 times a day with Artemia nauplii. After larviculture, there were no differences in the final lengths of larvae of the bold, shy, and mixed treatments (26.9 ± 0.76 mm, 26.7 ± 1.00 mm, and 26.8 ± 1.24 mm, respectively); however, shy larvae possessed weighed less (0.22 ± 0.01 g) than the bold and mixed treatments, which did not differ significantly (0.25 ± 0.02 g and 0.27 ± 0.02 g, respectively). The bold and mixed treatments had the highest cannibalism rate (11.2 ± 5.1% and 23.1 ± 12.3%, respectively). Overall survival was lowest in the mixed treatment (62.5 ± 13.0%), while that of the bold and shy treatments were similar (82.5 ± 9.2% and 86.2 ± 9.2%, respectively). The separation of L. alexandri larvae by traits can ensure a decrease in cannibalism and hence, more productive larviculture.