Postprandial Patterns of Digestive Enzyme Activity in Male Siamese Fighting Fish (Betta splendens)

Abstract

Postprandial changes in digestive enzyme patterns were investigated in male Siamese fighting fish (Betta splendens). The fish (1.58±0.03 g) were fasted for 24 h to empty the gut and then fed once before sampling postprandially. Specific activities of pepsin, trypsin, chymotrypsin, lipase, and amylase were determined, as well as ratios of trypsin/chymotrypsin and amylase/trypsin (n = 4). Over the 24-h postprandial observation, feces were not found for the first four hours of sampling, but 52.5% of the fish defecated within 24 h. Of all feces excreted, approximately 25% were counted at 5–6 h after feeding. Postprandial time had significant effects on all five of the enzymes (p<0.05), and higher specific activity than the control (0 h) was observed over the entire 24-h period of observation. Protein-, lipid-, and carbohydrate-digesting enzymes, as well as the trypsin/chymotrypsin ratio, exhibited similar patterns in response to time after feeding. The amylase/trypsin ratio at every postprandial time interval was significantly lower than the control at 0 h. The present study found that postprandial enzyme activities of male Siamese fighting fish changed gradually but were sustained for a relatively long period. These findings could inform the feeding regimen management of this species, particularly regarding suitable feeding frequency.