2. Materials and methods
2.1. Fish
Tilapia (O. niloticus) propagated and reared by the Research Institute for
Fisheries, Aquaculture and Irrigation (HAKI, Szarvas, Hungary) were used for
the experiment. Fish were fed with a dry feed, produced in the experimental
milling facility of the institute and kept in 2000 l fibreglass tanks in the
recirculation system of the institute at water temperature of 22–23 °C.