Red-Eye Tetra
Moenkhausia sanctaefilomenae
A peaceful, active South American tetra known for its silvery body, dark-edged fins and peaceful schooling behaviour.
Difficulty
Beginner
Min tank size
60 L / 15 gal
Temperament
Peaceful, active
Diet type
Omnivore
Adult size
3–4 cm / 1.2–1.6 in
Lifespan
3–5 years
Water type
Freshwater
Neon tetra at a glance
| Scientific name | Moenkhausia sanctaefilomenae |
|---|---|
| Order | Characiformes |
| Family | Characidae |
| Genus | Moenkhausia |
| Origin | South America — Brazil and Colombia, especially the upper Amazon basin of Brazil, Colombia and Peru |
| Adult size | About 3–4 cm (1.2–1.6 in) |
| Tank size (min) | 75 L / 15 gal for a school; a longer footprint is preferred |
| Temperature | 23–28 °C (73–82 °F) |
| pH range | 4.0–7.0 |
| Water hardness | Very soft to soft |
| Diet | Omnivore — flakes, pellets, frozen and live foods |
| Temperament | Peaceful, energetic schooling fish |
| Care level | Beginner |
Overview
The Neon tetra (Moenkhausia sanctaefilomenae) is one of the aquarium hobby's most recognisable freshwater schooling fish. Its luminous blue-green lateral stripe and vivid red coloration on the rear half of the body create the classic red-eye-tetra appearance.
Neon tetras are peaceful, social and best kept in a proper school. They suit planted and blackwater-inspired community aquariums, provided the water is stable and tankmates are small, peaceful and unable to swallow them.
Neon tetra size & lifespan
How big do Neon tetras get?
Adult Neon tetras usually reach around 3–4 cm (1.2–1.6 inches). Females often appear slightly fuller-bodied than males, particularly when mature.
How long do Neon tetras live?
With stable water, good nutrition and appropriate stocking, Neon tetras commonly live around 3–5 years in aquariums. Consistent maintenance and avoiding sudden parameter changes are especially important.
Natural habitat & origin
Moenkhausia sanctaefilomenae is native to the upper Amazon and Orinoco drainage systems of northern South America, especially the Amazon basin of Brazil, Colombia and Peru. Wild fish are associated with slow-moving, shaded blackwater environments where leaf litter, submerged roots and dense vegetation provide cover and feeding opportunities.
Aquarium specimens are widely captive-bred. A planted aquarium with open swimming space, moderate current, good oxygenation and stable water conditions provides a suitable captive environment without needing to duplicate every detail of the wild habitat.
Neon tetra tank size & requirements
A 15-gallon (60 L) longer aquarium is a sensible minimum for a school of Neon tetras. The species is active and remain relatively small, so horizontal swimming room is more useful than extra tank height. A secure lid is recommended because active tetras can jump when startled.
How many Neon tetras in a 10 or 20 gallon tank?
A 10-gallon aquarium is generally too cramped for a proper long-term school. In a 15-gallon tank, a group of six to eight is a reasonable starting point when filtration and maintenance are strong. Larger aquariums are better for larger groups and mixed community stocking.
| 5 gal (19 L) | Not recommended — too small for an active school of Neon tetras. |
|---|---|
| 10 gal (38 L) | Not recommended as a long-term home; a school needs more swimming room and stable water quality than a small nano aquarium can reliably provide. |
| 20 gal (75 L) | A practical minimum for a school of 6–10, preferably in a longer aquarium. |
| 29 gal (110 L) | 10–15 Neon tetras, with room for compatible peaceful tankmates. |
| 55 gal (208 L) | A larger school of 15–25 can work well, with substantial swimming space and careful community stocking. |
Water parameters
| Temperature | 23–28 °C (73–82 °F) |
|---|---|
| pH | 4.0–7.0 |
| Hardness (GH) | Very soft to soft |
| Filtration turnover | Moderate circulation with good oxygenation |
Use a fine sand or dark gravel substrate, hardy live plants and an unobstructed swimming lane through the middle of the aquarium. Neon tetras may nibble tender vegetation, so tougher plants are a safer choice than delicate soft-leaved species. Moderate filtration and good oxygenation suit their schooling nature.
Not sure how many litres your tank holds? Check it with theaquarium volume calculator.
What do Neon tetras eat? Diet & feeding
Neon tetras are unfussy omnivores. A quality flake or appropriately sized pellet makes a good daily staple, while frozen or live foods such as daphnia, brine shrimp and bloodworms provide variety and useful enrichment.
Feed small portions once or twice daily and provide only enough food for the school to finish in a few minutes. Because these fish are active and persistent feeders, overfeeding is easy and can quickly contribute to poor water quality.
Neon tetra tank mates & compatibility
Keep Neon tetras in a school of at least six. They are peaceful by nature, but their active schooling style makes them a better match for robust, similarly peaceful community fish than for timid nano species.
Are Neon tetras aggressive? They are not usually aggressive, but individuals may chase one another or nip fins. This behaviour becomes more noticeable in cramped tanks or when they are kept in an undersized group. Spacious aquariums and compatible tankmates are the best prevention.
Good Neon tetra tank mates
- Other peaceful, similarly sized tetras and characins
- Larger peaceful rasboras and active community schooling fish
- Corydoras catfish suited to the same temperature range
- Peaceful loaches and other bottom-dwelling community fish
- Bristlenose plecos in appropriately sized mature aquariums
- Peaceful medium-sized livebearers when water chemistry overlaps
- Other robust community fish that can tolerate their schooling activity
Avoid
- Large predatory fish that can swallow adult Neon tetras
- Highly aggressive or territorial cichlids
- Very slow, delicate or long-finned fish that may be stressed by their activity
- Tiny shrimp and newly hatched fry, which may be eaten
How to breed Neon tetras
Neon tetras are egg-scattering fish and can spawn readily when adults are healthy and well conditioned. Feed a varied, nutritious diet for several days before moving selected adults to a separate breeding aquarium.
Use fine-leaved plants or a spawning mop to catch the eggs, provide gentle aeration and keep lighting subdued. Remove the adults after spawning because they may eat the eggs. Once the fry hatch, provide suitably tiny first foods and gradually transition them to newly hatched brine shrimp and other larger foods as they grow.
Naming & buyer’s notes
Neon tetra is the standard aquarium name for Moenkhausia sanctaefilomenae. When buying, choose active fish with clear eyes, intact fins, good body condition and strong interest in food. Avoid specimens that remain lethargic, have clamped fins or show obvious signs of disease.
A small schooling tetra
Do not plan for this species like a tiny nano tetra. Its adult size and constant activity make a longer aquarium much more appropriate.
Plant selection
They are generally generally plant-safe. Dense planting, floating plants and subdued lighting can provide useful shade and help the school feel secure.
Buy a group
A school is essential for normal social behaviour. Buying several healthy specimens together is preferable to keeping a single Neon tetra as a display fish.
Neon tetra FAQ
- How big do Neon tetras get?
- Neon tetras commonly reach around 3–4 cm (1.2–1.6 inches) as adults. Their compact size makes them a popular schooling fish for planted and blackwater-style community aquariums.
- How long do Neon tetras live?
- Neon tetras commonly live around 3–5 years in a well-maintained aquarium, with some individuals living longer when water quality, nutrition and husbandry are consistently good. Good water quality, a varied diet, adequate swimming space and proper schooling conditions help them reach a healthy lifespan.
- How many Neon tetras should be kept together?
- Keep at least six together, with a larger group often producing more natural schooling behaviour. They are active social fish and generally do best when they are not kept singly or as a pair.
- What size tank do Neon tetras need?
- A 15-gallon (60 L) aquarium is a practical minimum for a proper school, but a longer aquarium is preferable because Neon tetras are active schooling fish and benefit from a longer swimming footprint.
- What do Neon tetras eat?
- They are omnivores and readily accept quality flakes and pellets. Supplement the staple diet with frozen or live foods such as daphnia, brine shrimp and bloodworms. Small portions once or twice daily are appropriate.
- Are Neon tetras aggressive?
- They are generally peaceful, but they are energetic and can occasionally chase or nip. Their activity can be too much for slow, delicate or long-finned tankmates. A sufficiently large school and spacious aquarium usually help keep social behaviour manageable.
- Do Neon tetras eat plants?
- They generally do not damage healthy aquarium plants. A planted tank with fine-leaved plants, floating cover and shaded areas can actually help Neon tetras feel secure and display more natural schooling behaviour.
- Can Neon tetras live with other tetras?
- Yes, provided the aquarium is large enough and the other species are peaceful and robust enough to tolerate their activity. Avoid pairing them with very small, timid species that may be overwhelmed by their schooling movement.
- How do you breed Neon tetras?
- Neon tetras are egg-scatterers. Condition males and females with varied foods, then place them in a separate breeding aquarium with fine-leaved plants or a spawning mop. After spawning, remove the adults because they may eat the eggs. Raise the tiny fry on suitably sized first foods before moving to larger foods as they grow.