Ide
Leuciscus idus
The ide is a medium to large freshwater fish with a slightly laterally compressed body. It is characterized by its silvery coloration and reddish fins, while cultivated varieties like the golden orfe are strikingly orange. It primarily inhabits slow-flowing rivers and lakes across Europe and Asia and belongs to the whitefish group.
Details
Identification
Small scales, terminal mouth, yellow iris, reddish coloration of pelvic and anal fins.
Social behavior
Schooling fish forming large groups especially when young; older individuals often live in smaller groups.
Diet
Omnivorous, with a diet ranging from insect larvae, snails, and crustaceans to small fish and algae.
Hunting strategy
Active searching for food both on the water bottom and at the water surface (terrestrial insects).
Spawning substrate
Gravelly substrate, stones, or submerged aquatic plants.
Overwintering
Overwintering in deep, low-current zones at the bottom of the water body with a reduced metabolism.
Ecology
Ecological role
Important component of the food web as both a consumer and prey for larger predatory fish and birds.
Natural predators
Pike, zander, cormorant, grey heron, and otter.
Competitor species
Other whitefish species such as chub, roach, and bream.
Ecosystem service
Contributes to biodiversity and supports the nutrient cycle in water bodies.
Threats
Destruction of spawning grounds through river straightening, barriers, and water pollution.
Scientific profile
Morphology & ID
Coloration
Back olive-green to bluish-black, sides silvery, belly white; pectoral, pelvic, and anal fins reddish.
Distinguishing features
Small scales (55-63 along lateral line), terminal mouth, anal fin concave (curved inwards).
Confusion species
Chub (Squalius cephalus): larger scales, convex anal fin. Roach (Rutilus rutilus): red iris, larger scales.
Sexual dimorphism
Males are usually slightly smaller and slimmer than females of the same age and develop fine nuptial tubercles during the spawning season.
Habitat
Fish region
Bream zone (metapotamal) and ruffe-flounder region (oligohaline zone).
Preferred zone
Prefers the open water zone (pelagic) and near-shore areas (littoral) of large, slow-flowing rivers and lakes.
Flow preference
Potamophilous; prefers slow-flowing water, avoids strong currents.
Substrate preference
Sandy or gravelly bottom, also tolerates muddy substrates in standing waters.
Oxygen requirement
Moderate; requires approx. 5-7 mg/L oxygen for optimal growth.
Migration
Migration behaviour
Potamodromous; undertakes spring migrations from lower reaches or lakes upstream into smaller tributaries to the spawning grounds.
Reproduction
Spawning substrate
Phytolithophil; laicht auf Wasserpflanzen, Wurzeln oder Kies ab.