Clithon retropictus (Clithon retropictus) — 2cm

Overview

Clithon retropictus is a small peaceful algae-grazing nerite snail from East Asian freshwater and brackish habitats that provides effective algae control whilst adding unique horned shell character to aquariums. Available for sale UK through Tropical Fish Co, this hardy species reaches just 2cm making it ideal for nano aquariums and small community setups. The easy care requirements and peaceful temperament make it suitable for aquarists of all experience levels seeking functional cleanup crew members. The distinctive shell patterns and grazing behaviour help maintain clean glass and décor whilst requiring minimal specialist care beyond appropriate water chemistry.

Appearance and Shell Structure

Clithon retropictus displays compact globular shell reaching 2cm diameter with characteristic nerite snail structure. The shell surface shows variable patterning depending on individual—typically featuring spots, stripes, or zigzag patterns in combinations of black, brown, orange, and cream colours. Some specimens develop small horn-like projections on the shell, giving rise to "horned nerite" designation though this feature is variable. The operculum (door) allows complete retraction into shell for protection. The muscular foot is typically grey to olive-green, well-adapted for strong adhesion to surfaces during grazing. Two sensory tentacles extend from the head region for navigation and detecting food sources.

Natural Habitat

This nerite snail inhabits freshwater rivers, streams, and brackish coastal habitats throughout East Asia, particularly Japan and Korea. These environments feature rocks, submerged wood, and various hard surfaces supporting algae and biofilm growth. Water ranges from purely freshwater inland systems to slightly brackish estuarine zones where freshwater meets tidal influence. Temperatures fluctuate seasonally more than tropical systems, experiencing cool periods during winter whilst warming substantially in summer. The snails graze continuously on aufwuchs coating surfaces, moving slowly across substrate using muscular foot. Natural habitats typically have neutral to alkaline pH with moderate to high mineral content supporting shell growth and maintenance.

Aquarium Setup

Clithon retropictus adapts to aquariums from 10 litres upward, making it suitable for nano tanks through large displays. Provide smooth hard surfaces (glass, rocks, driftwood, decorations) that develop natural algae growth for grazing. Substrate type is flexible as these snails spend time primarily on vertical and horizontal surfaces rather than burrowing. Lighting can be moderate to bright to support algae growth providing natural food source. Filtration should maintain good water quality and oxygenation. These snails tolerate various setups from heavily planted tanks to minimalist aquascapes, though natural algae presence or supplementary feeding is essential. Ensure aquarium has tight-fitting lid as nerite snails occasionally climb above waterline and may escape if gaps exist.

Water Parameters and Shell Health

Maintain temperatures between 18-26°C—notably tolerant of cooler conditions than many tropical species. Critical parameter is pH: must be neutral to alkaline 7.0-8.5 with 7.5-8.0 being ideal. Acidic water below 7.0 gradually dissolves calcium carbonate shells causing erosion and pitting. Hardness should be moderate to high (8-15 dGH or higher) providing dissolved minerals for shell maintenance and growth. Ammonia and nitrite must remain at zero, whilst nitrates should be kept below 20ppm through regular water changes. These hardy snails tolerate varying water conditions better than many aquatic invertebrates, but shell health depends absolutely on adequate mineral content and alkaline pH. Avoid copper-based medications which are lethal to all invertebrates.

Feeding and Algae Grazing

Clithon retropictus is primarily an algae and biofilm grazer that provides valuable algae control in established aquariums. The snails rasp algae from glass, rocks, wood, and decorations using radula (ribbon of microscopic teeth), leaving clean trails behind them. In mature tanks with natural algae growth, supplementary feeding may be unnecessary. In pristine algae-free tanks, supplement with blanched vegetables (courgette, cucumber, spinach), quality algae wafers, or spirulina-based foods placed near snails 2-3 times weekly. Calcium-rich foods support shell health—cuttlebone or specialized snail foods containing added minerals are beneficial. These efficient grazers work tirelessly but should not be relied upon solely as cleanup crew—provide dedicated feeding to ensure adequate nutrition for long-term health.

Behaviour and Activity Patterns

Nerite snails are constantly active grazers showing no strict diurnal or nocturnal pattern—they feed continuously whenever hungry. Movement is characteristically slow and methodical as they rasp surfaces systematically. The muscular foot adheres powerfully to surfaces allowing navigation of vertical glass, inverted positions under décor, and movement through gentle current. They occasionally rest motionless for extended periods (hours to a day) which is normal behaviour—only snails remaining withdrawn for multiple days with foul odour require removal. Unlike some snails, Clithon species cannot reproduce in purely freshwater aquariums (larvae require brackish/marine conditions), preventing population explosions that plague some snail species. This makes them ideal cleanup crew members without risk of overpopulation.

Compatible Tank Mates

These peaceful snails coexist harmoniously with most community fish and peaceful invertebrates. Suitable tankmates include small peaceful community fish (tetras, rasboras, livebearers), peaceful shrimp species, and other peaceful snails. The hard operculum-protected shell provides defense against casual harassment, though dedicated snail predators pose risk. Exclude loaches (especially Botia and Chromobotia species that specialize in snail predation), pufferfish (which consume snails as primary diet), aggressive predatory cichlids, crayfish (which may catch and consume snails), and large predatory fish. Snail-eating assassin snails should obviously also be avoided. Most peaceful community fish ignore nerite snails entirely.

Breeding

Whilst Clithon retropictus adults thrive in freshwater, successful reproduction requires brackish to marine conditions for larval development. Adults may lay distinctive white sesame seed-like egg capsules on aquarium glass, rocks, and decorations—these are extremely adhesive and difficult to remove but will not hatch in freshwater. The eggs are harmless but some aquarists find them aesthetically displeasing. Larvae require brackish/marine salinity to develop through planktonic stages before metamorphosing into juvenile snails capable of freshwater life. Captive breeding in home aquaria is therefore uncommon and requires specialized brackish rearing systems. This reproductive limitation means nerite snails cannot overpopulate tanks unlike many other snail species.

Why Buy from Tropical Fish Co

Tropical Fish Co supplies healthy, active Clithon retropictus specimens with intact undamaged shells and normal grazing behaviour. Each snail is hand-selected to ensure you receive robust individuals ready to provide effective algae control in your aquarium. Our experienced staff can advise on maintaining appropriate water chemistry for shell health and compatible tankmate selection. With specialist packaging ensuring safe transit and next-day UK delivery, your new snails arrive in excellent condition ready to begin their cleanup duties. We're committed to sustainable sourcing and work only with responsible suppliers who prioritize invertebrate welfare.