Costae Tetra

Costae Tetra, also known as Blackline Tetra or Costa's Tetra, is an attractive freshwater schooling fish loved for its streamlined body, active swimming style, and clean dark line running along the flank. This species does best in groups and brings constant movement to the middle area of the aquarium, making it a strong choice for peaceful community tanks. Its alert nature and hardy behaviour make it suitable for aquarists who want an energetic tetra with a natural shoaling display.

When kept in a proper school, Costae Tetra shows better confidence, tighter group movement, and more natural behaviour. It pairs well with other peaceful community fish of similar size and enjoys a well-maintained aquarium with open swimming space, gentle flow, and stable water conditions. A planted setup with darker substrate can help its body line stand out even more.

Key Features

• Appearance: Slender silver body with a noticeable dark horizontal stripe that gives the fish its Blackline Tetra common name.
• Size: Usually sold as small juvenile aquarium fish and can grow to around 6 to 8 cm in good conditions.
• Colors: Metallic silver base tone with darker body marking; fins are generally subtle and natural rather than flashy.
• Lifespan: With stable water quality, quality food, and low stress, this tetra may live around 3 to 5 years in home aquariums.
• Temperament: Peaceful, active, and social; best kept in a group rather than singly or in pairs.
• Water Type: Freshwater species suited to tropical community aquariums.

Care Requirements

• Tank Size: A tank of at least 60 litres is recommended for a proper school, though larger aquariums offer better swimming room and more stable conditions.
• Water Parameters: Ideal temperature is around 22 to 28°C with pH near 6.0 to 7.5. Stable, clean water is more important than chasing exact numbers.
• Diet: Omnivorous and easy to feed on quality micro pellets, flakes, crushed granules, and occasional frozen or live foods like daphnia or bloodworms.
• Tank Mates: Suitable with rasboras, other peaceful tetras, Corydoras, small gouramis, and similarly calm community fish. Avoid large aggressive tank mates.
• Schooling Need: Keep at least 6 to 8 together, with bigger groups often showing the best colour, confidence, and natural movement.
• Care Tips: Provide open swimming space in the centre, some plants around the sides and back, regular water changes, and a secure lid for a calm, stable setup.

Costae Tetra is a practical choice for hobbyists building an active freshwater community aquarium. Buying a group instead of a single specimen helps reduce stress and brings out the best schooling behaviour in this species.