Red Eye Tetra - Mounkhosia sanciaefilomene

Red Eye Tetra (Bario sanctaefilomenae) The Red Eye Tetra is an attractive and active freshwater shoaling fish recognised for its shimmering silver body, distinctive bright red eyes and bold black marking at the base of its tail. Also known as the Red-Eyed Tetra or Yellow-Banded Moenkhausia, this hardy South American species is a popular choice for established tropical community aquariums. Its peaceful but energetic nature makes it particularly suitable for larger planted aquariums containing similarly active fish. When maintained in a good-sized group, Red Eye Tetras create an appealing display as they swim together through the middle and upper sections of the aquarium. Common Name: Red Eye Tetra, Red-Eyed Tetra, Yellow-Banded Moenkhausia, Saint Filomena Tetra Scientific Name (Latin): Bario sanctaefilomenae (formerly Moenkhausia sanctaefilomenae) Maximum Size: Approximately 6–7 cm, with some mature specimens reaching around 7 cm body length excluding the tail Water Type: Freshwater Origin / Natural Habitat: The Red Eye Tetra originates from South America, with populations occurring across river systems in Brazil, Paraguay, Argentina and neighbouring regions. Wild Bario sanctaefilomenae inhabit freshwater rivers, tributaries, lagoons and slower-moving waterways, particularly within the Paraná, Paraguay and other South American river drainages. These environments commonly feature submerged vegetation, marginal plant growth, roots and areas of open water where groups of fish can swim and feed. Unlike some specialist blackwater tetras, Red Eye Tetras naturally experience a range of water conditions, making them relatively adaptable when maintained in established aquariums. Most Red Eye Tetras available within the aquarium trade are captive-bred rather than collected from wild populations. Water Parameters: Temperature: 22–26°C pH Range: 6.0–8.0 Hardness: Soft to Hard, approximately 3–20 dGH Ammonia/Nitrite: 0 ppm Nitrate: Kept low and stable Temperament: Peaceful to Semi-Aggressive Red Eye Tetras are generally peaceful, active shoaling fish that are well suited to community aquariums containing similarly sized and energetic species. They should be maintained in groups of at least 8–10 individuals, with larger groups recommended where aquarium space allows. Although not normally aggressive, Red Eye Tetras can be boisterous and may occasionally nip the fins of slower-moving or long-finned fish, particularly when kept in insufficient numbers. They are best housed with robust but peaceful tankmates that can comfortably accommodate their active swimming behaviour. Avoid very small, timid or delicate species that may become intimidated or outcompeted during feeding. Diet: Omnivore Red Eye Tetras naturally feed on small insects, aquatic invertebrates, crustaceans and other available food organisms, alongside some plant material. In the aquarium, they readily accept a varied diet of high-quality tropical flakes, small pellets and fine granules. Their diet can be supplemented with frozen or live foods such as brine shrimp, daphnia, bloodworm, cyclops and small mosquito larvae. Occasional vegetable-based foods can also be offered to provide additional dietary variety. A balanced feeding routine helps maintain healthy growth, natural colouration and good overall condition. Offer small portions once or twice daily, ensuring food is distributed throughout the group. Minimum Tank Size: Approximately 110 litres Red Eye Tetras are active swimmers that require generous horizontal swimming space, particularly when maintained in larger groups. An aquarium measuring at least 90 cm in length is recommended, with larger aquariums preferable for substantial shoals or mixed community setups. Provide open swimming areas alongside planted sections, driftwood and natural shelter. Although relatively hardy, their adult size and energetic behaviour mean they are not suitable for very small aquariums. Behaviour & Activity: The Red Eye Tetra is a lively midwater swimmer that frequently moves throughout the middle and upper regions of the aquarium. Its bright red eyes and contrasting black tail markings make it particularly noticeable when swimming in groups. Red Eye Tetras naturally form loose shoals, often swimming together while exploring open areas and searching for food. Occasional chasing and short displays between individuals are normal, although this behaviour is generally less disruptive when the fish are maintained in sufficiently large groups. They are enthusiastic feeders and may compete strongly for food, so care should be taken when housing them with slower or more timid species. A well-planted aquarium containing open swimming areas allows them to display their natural activity while providing sheltered areas when required. Community Suitability: Community Fish / Semi-Aggressive Red Eye Tetras are suitable for established freshwater community aquariums containing active, similarly sized fish. Suitable companions include other robust peaceful tetras, medium-sized rasboras, peaceful barbs, rainbowfish, Corydoras catfish and other non-aggressive species with compatible water requirements. They are particularly well suited to larger planted community aquariums where their lively swimming behaviour can be accommodated without disturbing more delicate inhabitants. Avoid slow-moving, long-finned fish such as fancy guppies or veil-tail varieties, as occasional fin-nipping may occur. Very small or timid species may also struggle to compete with Red Eye Tetras during feeding. Maintaining a good-sized group helps encourage natural social behaviour and reduces the likelihood of individual fish repeatedly harassing their tankmates. Special Requirements or Care Notes: Provide a mature, well-maintained freshwater aquarium with stable water chemistry and efficient biological filtration. Red Eye Tetras are naturally active shoaling fish and should be maintained in groups of at least 8–10 individuals. Allow generous horizontal swimming space, as this species is more energetic than many smaller tetra varieties. Include planted areas, driftwood and natural shelter while leaving sufficient open water for swimming. Although relatively adaptable to different water conditions, sudden changes in temperature, pH or hardness should be avoided. Regular partial water changes are important for maintaining excellent water quality and keeping nitrate levels under control. Red Eye Tetras are enthusiastic feeders and should receive a varied diet of quality prepared foods alongside occasional frozen or live foods. Avoid housing them with delicate, long-finned or particularly timid fish, as their boisterous behaviour may cause stress or occasional fin damage. A secure aquarium lid is recommended, as active tetras may jump when startled. This species is an egg-scattering fish, with adults showing no parental care and potentially consuming their own eggs. Successful breeding generally requires a separate breeding aquarium. Most specimens available in the aquarium trade are captive-bred and are generally adaptable to established tropical aquarium conditions. Suitable for: Beginner to Intermediate Availability: Common / Regularly Available / Captive-bred All images are a visual representation of the fish you will receive, made to be as accurate as possible. Please note that Mother Nature is a wonderful thing, and variation in patterns and colours will occur — that is part of the unique beauty of these animals.