Marisa cornuarietis red (Marisa cornuarietis) — 1-2cm

Overview

Marisa cornuarietis, commonly known as the Giant Ramshorn Snail, is a hardy attractive herbivorous snail from South American freshwater systems that provides algae control whilst adding visual interest to aquariums. Available for sale UK through Tropical Fish Co in striking red colour form, this substantial species reaches 5cm shell diameter making it one of the largest commonly kept aquarium snails. The easy care requirements and peaceful temperament make it suitable for aquarists seeking effective cleanup crew members, though plant damage potential requires consideration. The species' prodigious appetite for algae and plant matter makes it functionally beneficial whilst its size and coloration create impressive display.

Appearance and Red Coloration

The Giant Ramshorn Snail displays characteristic planispiral (flat-coiled) shell typical of Planorbidae family, reaching impressive 5cm diameter at maturity. The red form offered features striking blood-red to orange-red shell coloration—a selectively bred variant of the species that shows much more vibrant colour than wild-type brown forms. The shell shows multiple whorls coiling outward from centre, visible from both sides as the shell is flattened rather than conical. The muscular foot is typically pink to red matching shell colour, extending substantially during movement. Two triangular tentacles with eyes at the base provide sensory information. The mantle (body tissue lining shell) may be visible through shell aperture, often showing spotted or mottled patterns.

Natural Habitat

Marisa cornuarietis inhabits freshwater rivers, streams, ponds, and wetlands throughout northern South America, particularly Caribbean lowlands and river systems of Colombia and Venezuela. These tropical environments feature still to slow-flowing water with abundant aquatic vegetation, soft substrates, and variable water chemistry. The species occupies areas rich with algae, aufwuchs, and soft plant matter constituting primary diet. Natural populations have been introduced to other tropical regions where they sometimes become invasive due to rapid reproduction and voracious plant consumption. Water temperatures remain warm year-round with seasonal variations in water levels but relatively stable chemistry.

Aquarium Setup

Provide minimum 40-litre aquarium allowing adequate space for these substantial snails. Substrate type is flexible—sand, gravel, or planted tank substrates all work. However, plant selection is critical: only include robust hardy species (Anubias, Java fern, tough Amazon swords) or artificial plants if maintaining live plants is priority. These snails will damage and consume soft delicate plants enthusiastically. Filtration should maintain good water quality and oxygenation. Lighting can be moderate to bright. Ensure secure tight-fitting lid as Giant Ramshorns occasionally climb above waterline and may escape through gaps. Provide calcium-rich environment through appropriate water chemistry and supplementary calcium sources (cuttlebone, calcium-rich substrates) to support shell growth and maintenance.

Water Parameters and Shell Health

Maintain temperatures between 21-27°C. This species tolerates broad pH range 6.0-8.0, offering flexibility in community setups, though neutral to slightly alkaline (6.8-7.5) is ideal. Hardness should be low to moderate (5-12 dGH) with adequate dissolved minerals supporting shell development. Ammonia and nitrite must remain at zero, whilst nitrates should be kept below 20ppm through regular water changes. These hardy snails tolerate varying conditions better than many invertebrates, though shell health depends on adequate calcium availability. Avoid copper-based medications which are lethal—many fish medications contain copper. Soft highly acidic water may gradually erode shells; add mineral supplements if water is naturally very soft.

Feeding and Herbivorous Diet

Marisa cornuarietis is primarily herbivorous with voracious appetite for algae, biofilm, and soft plant matter. In aquariums with natural algae growth, they provide valuable cleanup services rasping algae from glass, rocks, and decorations. However, they will also consume soft aquarium plants enthusiastically—this is not occasional nibbling but serious plant destruction. Supplement with blanched vegetables (courgette, cucumber, spinach, lettuce) weighted to sink, quality algae wafers, and spirulina-based foods offered 2-3 times weekly. Calcium-rich foods support shell growth—cuttlebone or specialized snail foods containing added minerals are beneficial. Remove uneaten food after 24 hours to prevent water quality issues. Despite being cleanup crew, provide dedicated feeding to ensure adequate nutrition.

Behaviour and Activity Patterns

Giant Ramshorn Snails are continuously active grazers showing activity throughout day and night with no strict diurnal pattern. Movement is characteristically slow and methodical as they rasp surfaces systematically using radula. The large muscular foot allows surprisingly good adhesion despite the snail's substantial size and weight. They navigate vertical surfaces, though less confidently than smaller species. Breeding behaviour is notable—these snails reproduce readily in freshwater (unlike nerite snails) laying gelatinous egg masses on hard surfaces. Eggs are typically deposited on glass, decorations, or plant leaves near or above waterline. Egg masses contain numerous individual eggs visible as small spheres within jelly matrix. Juveniles hatch within 1-2 weeks and grow rapidly with adequate food and calcium.

Compatible Tank Mates

These peaceful snails coexist well with most community fish and peaceful invertebrates. Suitable tankmates include peaceful community fish (tetras, rasboras, livebearers, peaceful barbs), peaceful shrimp that aren't predatory, and other peaceful snail species. The substantial size and hard shell provide defense against casual harassment. However, exclude dedicated snail predators: loaches (particularly Botia species), pufferfish (which eat snails as primary diet), aggressive large cichlids, crayfish (which may catch and consume snails), and assassin snails. Most peaceful community fish ignore the large ramshorns entirely. Unlike nerite snails, these can breed prolifically—manage population through egg mass removal if preventing population explosion is desired.

Breeding

Marisa cornuarietis breeds readily in freshwater when conditions are stable and food is abundant. Unlike nerite snails, these complete their entire lifecycle in freshwater. They are hermaphroditic (both male and female organs) but typically cross-fertilize with partners rather than self-fertilizing. Eggs are laid in distinctive gelatinous clutches containing 50-200 eggs on hard surfaces, often on aquarium glass near waterline or just above. Egg masses are clearly visible as clear jelly containing individual egg capsules. Incubation takes 1-2 weeks depending on temperature, with juveniles emerging as miniature versions of adults. Growth is rapid with adequate food and calcium. Population can increase quickly—remove egg masses if limiting numbers is desired. Juveniles are hardy and easy to raise on same diet as adults.

Why Buy from Tropical Fish Co

Tropical Fish Co supplies healthy, active Marisa cornuarietis red specimens with vibrant colouration and intact shells. Each Giant Ramshorn is hand-selected for excellent shell condition and normal grazing behaviour, ensuring you receive impressive snails ready to provide algae control (and plant consumption) in your aquarium. Our experienced staff can advise on maintaining appropriate water chemistry for shell health, managing breeding populations, and realistic assessment of plant compatibility (answer: not compatible with delicate plants). With specialist packaging ensuring safe transit and next-day UK delivery, your new snails arrive in excellent condition. We're committed to sustainable sourcing and work only with responsible suppliers who prioritize invertebrate welfare.