Influence Of Temperature On The Digestive Enzyme Activity And Respiration Frequency Of Pterophyllum Scalare

This paper discusses the domestic and foreign researches on fish digestive enzyme and study the influence of the temperature on the digestion, respiration in Pterophyllum scalare. In this paper, the author discusses: (1)Three main digestive enzymes'most appropriate reaction temperature on Pterophyllum scalare; (2)The influence of culture water temperature on three main digestive enzymes'activeness of Pterophyllum scalare; (3) The influence of culture water temperature on breathing frequency of juvenile fish and adult fish . The results are as follows:1. In 10 minutes reaction time with pH7.5,the activeness of protease's most appropriate reaction temperature measured in Pterophyllum scalare is 45oC.In 5 minutes reaction time with pH6.9, the most appropriate reaction temperature of amylase measured in Pterophyllum scalare is 40oC. In 60 minutes reaction time with pH7.5, when the most appropriate reaction temperature of lipase measured in Pterophyllum scalare is 30oC to 35oC. The experiment result shows that the activeness of protease's most appropriate reaction temperature is higher than that of amylase and lipase in Pterophyllum scalare, which is similar to other fish.2. When the temperature condition of the culture water is between 16oC to 25oC, the activeness of lipase and protease in Pterophyllum scalare decreases with temperature. Their most appropriate reaction temperature is 25oC, which has little difference with that of 22oC (P> 0.05).The activeness of amylase's most appropriate reaction temperature is 22oC, which has little difference with that of 25oC (P> 0.05).Thus, when the water temperature is 22oC, it has little influence on the digestion of Pterophyllum scalare.3,Every two days, when the water temperature was lowered 3oC, and the respiratory frequency of the juvenile fish and adult fish was measured under the water temperature of 25oC,22oC,19oC,16oC respectively. The results shows that at 25oC , respiratory frequencies of juvenile fish and adult fish were both the highest, that is, adult fish 122 times / min, juvenile fish 125.2 times / min. At 16oC, respiratory frequencies are the lowest, that is, adult fish 56.2times / min, juvenile fish 44.3 times / min. Also, every seven days, the water temperature was lowered 3oC, and the respiratory frequency of the juvenile fish and adult fish was measured under the water temperature of 25oC,22oC,19oC,16oC respectively. The results also shows that at 25oC, respiratory frequencies of juvenile fish and adult fish were both the highest, that is, adult fish 122.5 times / min, juvenile fish 125 times / min. At the water temperature of 16oC, respiratory frequencies are the lowest, that is ,adult fish 55.7times / min, juvenile fish 30.2 times / min.The research results show that the influence of temperature on the Pterophyllum scalare breathing frequency is not linear. Furthermore, the temperature has more obvious influence on the breathing frequency of juvenile Pterophyllum scalare than that on adult Pterophyllum scalare.In addition, when the interval of cooling time was extended, the Pterophyllum scalare's adaptability to hypothermia also was enhanced and it can live normally between 19oC～22oC. But juvenile Pterophyllum scalare's adaptability to hypothermia is lower than that of adults.In summary, this paper preliminarily discussed the influence of temperature on Pterophyllum scalare's digestion physiology and respiration .It is discovered that in the culture water temperature of 16～25 oC, the activeness of lipase and protease in Pterophyllum scalare decreased with temperature, the influence of temperature on the Pterophyllum scalare breathing frequency was not linear, and that the temperature had significant influence on the breathing frequency of juvenile Pterophyllum scalare than that on adult fish. These results provide some basic data and biology reference for the fish digestion physiology and the adaption to low temperature.This article suggested that the water temperature of 22 oC did not affect Pterophyllum scalare 's digestion, that lengthening the decreasing time-gap of temperature would be advantageous to Pterophyllum scalare 's compatibility to low temperature,and that the juvenile fish's adaptiveness to the low temperature was inferior to the adult fish. All these research results may be useful for the cultivations of Pterophyllum scalare and other tropical fishes.