The early development of the lateral-line systems in Eurasian perch (Perca fluviatilis) and the ruff (Gymnocephalus cernua) is described and related to development of behavior patterns characteristic of the two species. Perch are active pelagic predators for whom vision is of greatest importance in obtaining food, whereas ruff are benthophages of slow-flowing waters and typically obtain their food as solitary ambush predators for whom the highly sensitive lateral-line system is extremely important. The less developed system of the perch seems to match its greater ecological plasticity. Key words: Percidae, Perca, Gymnocephalus, lateral line, development, behavior, sensory organs

No abstract