The digestive enzymatic activity of Northeastern Siamese tigerfish (Datnioides undecimradiatus) in Mun river on Ubon Ratchathani province

Abstract

Northeastern Siamese tigerfish, Datnioides undecimradiatus is one of the most economically  ornamental freshwater fish. Currently the wild population has decreased dramatically, and found only in the Mun and the Mekong river. It is categorized in the Red List IUCN ((International Union for Conservation of Nature and Natural Resources) as vulnerable species (VU). The objective of the study was to determine the pattern of  digestive enzyme activity of Northeastern Siamese tigerfish i.e. protease, amylase and lipase respectively. Fish with four sizes of  45, 75, 100 and 200 g. respectively were collected from  the Mun river in Pibunmangsahan and Khongchium district of Ubon Ratchathani province, Northeast of Thailand. The results showed that all fish had the J – shape stomach with strong muscle which is the characteristic of carnivorous fish. The most highest value (P<0.05) of enzyme activity was found in protease of both stomach and intestine following by amylase and lipase respectively with significantly different. The highest protease activity  was found in 100 g. fish following by 45 g. fish with significantly different (P<0.05) i.e. 02±0.05 and 0.74±0.02 U/mg protein/min respectively. The highest amylase activity  was found in the intestine of 200 g. fish following by 75 g. fish which was found in the stomach with significantly different (P<0.05) i.e. 13.94±0.72 and 38.88±0.26 mU/mg protein/min respectively. The highest lipase activity was found in the stomach of  75 g. fish following by the intestine of 45 g. i.e. 0.62±0.09 and 0.42±0.05 mU/mg protein/min respectively. Lipase activity in the stomach showed significantly different among sizes (P<0.05) while lipase activity in the intestine showed no significantly different among sizes(P>0.05) . As the enzyme activity pattern of fish showed the protease activitiy in the digestive tract of all fish was highest and significantly higher than (P<0.05) the amylase and lipase activitiy, it is the characteristic of carnivorous fish’s digestive tract which digest most of dietary protein.