O2 requirements of the air-breathing fishes Pangasius hypophthalmus and Channa striatus
The air-breathing fish, Pangasius hypophthalmus and Channa striatus, are two of the most important fish species in the aquaculture of the Mekong Delta in Vietnam. In particular Pangasius aquaculture is in rapid growth and is now a common consumer item in European supermarkets. However, there is a fundamental lack of knowledge on the respiratory physiology of these species and growth in this industry poses a major threat to the freshwater environment in tropical river systems. Aeration of aquaculture markedly improved aquaculture in industrialised countries during the 1990's and dramatically improved effluent quality as well as bringing improvements in growth. It is unknown whether a similar improvement can be brought to the tropical aquaculture industry where there is a reliance on air-breathing species, although the little existing information suggests that a similar improvement could indeed be achieved with forced aeration. To properly resolve this important question, basic knowledge of respiratory physiology in relevant species is urgently needed. This project will study the respiratory physiology of P. hypophthalmus and C. striatus under controlled environmental conditions of oxygen saturation, digestion and temperature. Through the use of state of the art oxygen level transmitters and implantable heart-rate loggers this detailed knowledge of metabolism, obtained under experimental conditions, will be correlated to free living animals in fish-farming systems. This will enable the accurate estimation of oxygen requirements for animals in situ in aquaculture and provide the basic knowledge necessary for the design of optimal aeration and feeding systems.