HENRIK WEITKAMP1, WERNER KLOAS2,3, FRANK KIRSCHBAUM3, KURT-JOHANNES PETERS1, CARSTEN SCHULZ1
1Humboldt-Universität zu Berlin, Institute of Animal Science, Germany
2Humboldt-Universität zu Berlin, Department of Endocrinology, Germany
3Leibniz - Institute of Freshwater Ecology and Inland Fisheries, Germany
At present world aquaculture production is characterised by using only very few fish species. This led to an intercontinental drift and introduction of non-native fish species into aquatic habitats with no foreseeable ecological consequences. The low diversity of fish species used for aquacultural purposes is particularly caused in our restricted knowledge on reproduction biology of most fish species. The Bronze Featherback (Notopterus notopterus) is an important commercial fish for human consumption in Southeast Asia captured in natural habitats. In order to satisfy market requirements reproduction cycle should be investigated to ensure an aquacultural use.
Due to the fact that Bronze Featherback spawn in natural habitats during the rainy season, it can be suggested that environmental conditions seem to induce maturation and reproduction. Therefore the study is focused on the influence at varying conductivities (as we can find in the natural habitats during the rainy season) on gonad maturation.
The experiment comprises three groups with an average size of 20cm (n=30). In the first four weeks all fish are reared in a recirculation-system to ensure comparable environmental conditions. Afterwards, two groups of Notopterus notopterus will be kept under varying conductivities over a period of 8 weeks, while environmental conditions in group 3 are unchanged acting as control. Water conductivity in tank of group one decreases from 800 to 100 s/cm and simulating rainy season. Dry season is imitated in group two by a increasing water conductivity of from 800 to 1200 s/cm. Gonad maturation is determined by Gonado-Somatic-Index (GSI) and plasma steroid level (males: 11-keto-testosterone, females: estradiol) every 14 days.
It can be assumed, that simulation of rainy season conditions in terms of water conductivity will induce maturation of gonads, which control will be helpful for introduction Notopterus notopterus in aquaculture.
Keywords: Aquaculture, Notopterus notopterus, reproduction biology, gonad maturation