Food consumption by Eurasian perch (Perca fluviatilis L.) and ruffe (Gymnocephalus cernuus [L.]) was studied in single and mixedspecies treatments in the laboratory, where alternative food resources, chironomids and zooplankton, were offered simultaneously. The effects of structural complexity, which was represented by substrate grain size, and of feeding level on food consumption were analysed...

Since the 1980s, Swedish lakes have in general become less acidified. Assessment of biological recovery is, however, hampered by poor pre-acidification data, confounding effects of climate change, and few lakes with annual sampling of fish and other organisms. Only three critically acidified, but non-limed, lakes had two decades of fish monitoring. The lakes had not yet recovered to pre-industr...

Three iridovirus-like agents associated with systemic infections in fish were examined by electron microscopy, gel electrophoresis of virion polypeptides and serological cross reactions with hyperimmune rabbit sera. The virus associated with epizootic hematopoietic necrosis (EHN) of redfin perch Perca fluviatilis in Australia, the virus from sheatfish Siluris glanis in Germany and a recently is...