One of the keys for an optimal Eurasian perch aquaculture broodstock management is being able to determine sex individuals. For perch, compared with other methods identification fish and according 3R principle (replacement, reduction refinement), ultrasonography a rapid, non-lethal, non-invasive accurate method. During two successive experiments, we used ultrasound identify gender immature broo...

In the sample of 83 specimens of the perch (Perca fluviatilis L., 1758), caught on eight different sampling sites at the Vlasinsko Lake reservoir, in April–October 1993, 25 infested specimens were found. They were infested with the following species of parasitic ciliates: Trichodinella epizootica, Apiosoma robustum, Apiosoma piscicolum ssp. perci, Ichthyophthirius multifiliis, Chilodonella cypr...

The effect of group size on routine metabolic rate (RMR) and activity of the two shoaling percids Eurasian perch (Perca fluviatilis) and ruffe (Gymnocephalus cernuus) was studied using twin flow intermittent respirometry and time-lapse video techniques. In both species, we found a clear group effect. In isolated fish, oxygen consumption was up to two times as high as in groups of eight fish, wi...

Electron microscopical examination of gas gland cells of the physostome European eel (Anguilla anguilla) and of the physoclist perch (Perca fluviatilis) revealed the presence of significant numbers of lamellar bodies, which are known to be involved in surfactant secretion. In the perch, in which the gas gland is a compact structure and gas gland cells are connected to the swim bladder lumen via...