Author: (Linnaeus, 1758)
FBname: Ruffe
Comments: Inhabits eutrophic lakes, lowland and piedmont rivers.  Most abundant in estuaries 
  of large rivers, brackish lakes with salinities up to 10-12 ppt and reservoirs.  In general, its abundance increases with increased eutrophication (Ref. 59043).  Reported to prefer still or slow-flowing water with soft bottom and without vegetation (Ref. 59043) and deep water with deposits of sand and gravel (Ref. 9696).  Can tolerate some degradation of the environment (Ref. 30578).  Can co-exist in deep lakes with <i>Perca fluviatilis</i>.  Both species partly occur at different depths with <i>Gymnocephalus cernua</i> being more abundant in deeper layers (Ref. 59043).  The membranous external walls of the head canals of this species provide high directional sensitivity; can feed at night in the dark using the lateral line system; feeds on zooplankton, chironomids, oligochaetes and amphipods (Ref. 10999).  Pelagic in coastal lakes and tidal estuaries, preying on zooplankton and  fish.  Spawns on a variety of substrates at depths of about 3 m or less (Ref. 59043).  White to yellow eggs in sticky strands are found on rocks and weed in shallow water (Ref. 41678).  Used as bait for pike (Ref. 6258).  Females live up to 10 year while males up to 7 years (Ref. 59043).