Feeding energetics and angling catches of spangled perch, Leiopotherapon unicolor (Günther 1859), (Percoidei : Teraponidae)

Abstract

Spangled perch, Leiopotherapon unicolor, in aquaria reduced their daily ration as water temperature decreased. Fish held at a mean temperature of 16.8ºC did not grow significantly over a period of 180 days, whereas individuals maintained near 22.6ºC showed a weight increase of 32.8% over the same period. Both groups of fish metabolized approximately 38% of their energy intake, excreted 57% and allocated 5% for growth. Fish adapted to the lower temperature regime consumed 10.81 kJ day^-1 compared with a predicted value of 2.08 kJ day^-1 for fish adapted to warmer temperatures and exposed to 16.8ºC. Spangled perch appear to repartition energy resources at some point below 16ºC to make up for a shortfall in energy intake caused by reduced ration. Fish in their natural environment may also reduce food intake at low temperatures, as spangled perch caught by angling in winter had less food in their stomachs (0.31% body weight) than fish caught in other seasons (4.87% in spring to 3.13% in autumn). Catch rate in winter (< 1 fish per angler hour) was also lower than that in other seasons (> 5 fish per angler hour).