Red onion nerite
Vittina semiconica
The red onion nerite (Vittina semiconica), also called the Orange Track nerite, is a peaceful algae-grazing snail. It feeds mainly on growth coating glass, stones and décor, so it needs a mature aquarium with enough biofilm. A newly set-up or spotless tank may offer too little food. Adults live in fresh or brackish water, while the larvae require a marine phase. Egg capsules can therefore appear without creating a freshwater snail infestation in an ordinary aquarium.
Plan your aquarium →At a glance
- Temperature
- 22–28 °C
- pH
- 7.0–8.0
- Diet
- Herbivore
- Adult size
- Up to 3.5 cm
- Temperament
- Peaceful
About this species
Vittina semiconica (Lamarck, 1822) belongs to the family Neritidae. MolluscaBase/WoRMS accepts this name; Neritina semiconica is the older combination and basionym. Adults have a rounded to half-conical shell, often orange or reddish brown with dark spots or stripes. Aquarium references report roughly 2–3.5 cm. Pattern and colour vary, and related nerite snails can look very similar, so a trade name alone does not guarantee a precise identification.
Natural habitat
Aquarium references associate the species with Southeast Asia and Indonesia. Nerite descriptions include lower stream reaches, estuaries, lagoons and mangroves, where fresh and brackish water may meet. Exact collection locations for traded animals are not always known. Adults are kept in fresh or brackish water, but their larval development leads to the sea. This distinction matters: “freshwater snail” does not mean the entire life cycle can be completed in fresh water.
Aquarium and layout
Choose a mature, cycled aquarium with visible natural growth on glass, rock or wood. In a newly established or frequently scrubbed tank, available biofilm may be inadequate even when the water looks clear. A fixed minimum volume is not sufficiently consistent across sources; often quoted 30–54 litres are hobby guidelines, not a universal biological minimum. Match the number of snails to the real grazing surface and food supply. If an animal cannot right itself, place it gently with the shell opening downward. Use a secure lid because nerites may climb above the waterline and escape.
Water conditions
Aquarium profiles commonly overlap around 22–28°C. Published pH ranges vary: some keepers list about 6.5–8.5, while other guides give 7–8. We use 7–8 as a cautious practical band, not an experimentally established physiological limit. Neritids need mineral-containing water for shell growth, but exact GH and KH minima differ between sources and are not stored as verified central facts. Avoid abrupt changes, test ammonia/ammonium and nitrite if problems arise, and avoid copper-containing treatments that can harm invertebrates.
Behaviour and group size
The snail moves alone over hard surfaces and scrapes growth with its radula. It is generally peaceful and does not need to live in a group. Its foot can grip glass very firmly. Do not pull a firmly attached snail off with force, as this can damage the foot or shell. Some animals climb above the waterline; a lid reduces escape risk while allowing ventilation. If a snail remains still for a long time, first check whether it is alive and whether water conditions are stable; smell or a closed operculum alone is not a complete diagnosis.
Feeding
Its main food is algae, diatoms and biofilm growing on surfaces. This natural grazing is why a sterile or newly established tank is a poor choice. General algae wafers are sometimes suggested as supplements, but nerites do not always accept substitute foods and no central catalogue food has been confirmed as species-specific. We therefore do not link a branded product as guaranteed food. If you try a supplement, offer a small piece and remove leftovers promptly. Watch body condition and grazing activity; an animal that cannot find food needs a more mature environment.
Breeding
The sexes are separate, but they are difficult to distinguish externally. A female may deposit white, calcareous egg capsules on glass, stone or décor. These capsules are not proof of successful breeding. Larvae need a marine or sufficiently saline phase and do not complete development in an ordinary freshwater aquarium. You may therefore see egg capsules without getting a freshwater population. Remove capsules only if you find them unsightly; do not add salt to a community aquarium to try to hatch them.
Keeping with fish
Small, peaceful fish may be considered when both species can have stable, suitable water and the fish will not treat the snail as food. Shared water values alone do not establish a safe pairing. Large fish, puffers and known snail-eaters may peck at or consume it. The neon tetra (Paracheirodon innesi) is discouraged: its usual soft, slightly acidic water conflicts with the mineral-rich, neutral-to-alkaline direction recommended for a strong nerite shell. Do not alter water chemistry solely to force a combination.
Keeping with other invertebrates
Do not automatically combine this snail with predatory snails, crayfish or crabs. A predator such as Anentome helena eats other snails; no controlled aquarium trial of this exact pair was found, but plausible prey risk is enough to discourage the combination. Small shrimp are not assumed to be prey, although competition for surface growth and different water needs still matter. Keep stocking low enough for food to remain available and check that the nerite attaches and moves normally after introduction.
Exoskeleton, shell and minerals
The shell grows at its edge and depends on stable water with available minerals. Erosion or damage can have several causes, including low mineral availability, fluctuations or mechanical injury. Do not add calcium or hardness salts blindly: test first, then make gradual changes suitable for every tank inhabitant. A worn shell will not recover immediately when conditions improve. Avoid copper-containing medication in a tank with this snail unless the product is explicitly safe for invertebrates.
Possible problems
Common risks include starvation in an overly clean aquarium, escape over the rim, injury from forceful removal and shell erosion under unsuitable or unstable water conditions. Check the scientific name at purchase and ask about source and acclimation. A snail that lands upside down may not always right itself; help carefully without prying the shell open. Never release snails, egg capsules, aquarium water or plants into streams, ponds or the natural environment.
Keeping with other species
Neon tetra
Not recommendedDiscouraged: temperature may overlap, but the neon tetra is kept in soft, slightly acidic water (centrally recorded as GH 1–8 dGH and pH 6–7). Nerite sources recommend more mineral-rich, neutral-to-alkaline water. This is a long-term water-needs conflict, not a claim that the animals attack each other.
View species profile →Suitable plants
Dwarf Anubias
Conditional: Anubias tolerates this warm temperature band and its rhizome can be attached to wood or stone. Hard surfaces may develop the growth this snail grazes. The plant itself is not food and does not replace a mature aquarium with enough biofilm. This exact pairing has not been tested in a controlled trial.
- Light
- Low, Moderate
- CO₂
- CO₂ injection not needed
Sources & review
This care guide draws on several specialist sources and was last checked on .
View the sources
- MolluscaBase / World Register of Marine Species — Vittina semiconica (Lamarck, 1822)
- my-fish / WZF — Vittina semiconica – Ornament-Rennschnecke
- Aquarium Dietzenbach — Vittina semiconica – Orange Track Rennschnecke
- Aquarium Glaser GmbH — Vittina turrita und V. semiconica
- Fishipedia — Vittina semiconica – fiche mollusque
- Tropische Vissengids — Puntnapslak – Vittina semiconica
- Wikimedia Commons — Category:Vittina semiconica