Temperature and pH Characteristics of Amylase and Lipase at Different Developmental Stages of Siamese Fighting Fish (Betta splendens Regan, 1910)

Abstract

Temperature (20-80°C) and pH (2-12) profiles of amylase and lipase at three stages (10-dayold, 1.5-month-old and 3-month-old) in Siamese fighting fish (Betta splendens Regan, 1910) were studied. At least nine amylase activities were observed during development: pH 7 at 40°C, pH 9 at 30°C and 50°C, pH 8 and pH 11 at 50°C in females and pH 8 and pH 11 at 40°C and 60°C in males. At the younger stage (≤ 1.5 month old), activity at pH 7 and 40°C, and at pH 9 and 30°C and 50°C was observed. At the older stage (≥ 1.5 month old), amylase activity at pH 8 and pH 11 in the temperature range of 40-60°C was found. Lipase had at least five levels of activity: pH 7 at 20°C and 40°C, pH 8 at 20-40°C and 60°C, and at pH 11, where the activity peak disappeared in the maturing stage (3 month old) in both sexes. Amylase had very low specific activity at the 10-day-old stage, while lipase had a high specific activity, similar to older stages. The most suitable pH to determine amylase and lipase activity in Siamese fighting fish was pH 8, whereas a temperature of 50°C was appropriate for amylase and 40°C was suitable for lipase, regardless of sex and age. This information is a prerequisite for future studies of the in vitro digestibility evaluation of nutrient utilization in Siamese fighting fish.