Sunbleak / Moderlieschen

Geographic Origin and Biotope: Found across central and eastern European ponds, shallow lakes, and slow canals from France to Russia. Prefers vegetated waters with silty bottoms. Threatened in many areas by wetland destruction.

Taxonomy and Morphology: Small cyprinid (max 7-9 cm), fusiform, with large easily-shed (deciduous) silver scales. Small terminal upturned mouth. Incomplete lateral line extending only a few scales behind the operculum.

Social Behavior: Obligate schooler, extremely gregarious. Needs groups of 10-15+ to display natural schooling behavior. Alone, it hides terrified and refuses food.

Coloration and Sexual Dimorphism: Uniform brilliant silver with olive-green back. Breeding females develop a visible tubular ovipositor for wrapping eggs around plant stems in spirals.

Tank Setup: Ideal for temperate outdoor ponds or unheated 100+ liter cold-water aquariums. Dense thin-stemmed plants for spawning. Fine sand substrate.

Feeding: Surface/mid-water omnivore. Easily accepts fine flakes, daphnia, cyclops, and frozen brine shrimp. Not demanding.

Water Quality: Extremely wide tolerance: pH 6.5-8.5, any hardness, 4-25°C. NOT tropical: constant temperatures above 22°C reduce longevity. Untreated tap water is often perfect.

Compatibility: With other European coldwater cyprinids: White Clouds, Bitterlings, Minnows. Incompatible with tropical or large fish.

Reproduction: Unique: the female wraps eggs spirally around thin plant stems using adhesive secretion. 7-10 day incubation. No parental care.

Risks: Deciduous scales make it vulnerable to fungal infections (Saprolegnia) during handling. Overcrowding causes rapid asphyxiation.