The Moenkhausia costae, sometimes referred to as the Red-Costae Tetra, is a lesser-known gem from the Characidae family. At 2.5cm, these juveniles are lively, schooling fish that grow to reveal a stunning silver body with subtle reddish or golden reflections near the fins—making them a sleek, dynamic addition to community aquariums. Native to the slow-moving rivers and tributaries of South America, M. costae is peaceful, moderately hardy, and best appreciated in planted tanks where their shimmering bodies can stand out against lush greenery.

🐠 Key Features:

• Scientific Name: Moenkhausia costae

• Common Name: Costa Tetra, Red-Costae Tetra

• Size: 2.5cm (juvenile; adults can grow to 4–5cm)

• Lifespan: 3–6 years

• Temperament: Peaceful, active shoaler

• Difficulty: Moderate (due to need for stable water quality)

• Origin: South America (Amazon River basin)

• Ideal Group Size: 6 or more

🌊 Water Conditions

To ensure long-term health and full coloration, Moenkhausia costae should be kept in clean, well-oxygenated water with the following parameters:

• Temperature: 22–27°C (72–81°F)

• pH: 6.0–7.2

• Hardness: 3–10 dGH

• Tank Size: Minimum 15 gallons

• Water Type: Freshwater

• Filtration: Moderate flow; good oxygenation preferred

• Lighting: Moderate to bright (enhances their reflective coloration)

A planted setup with open swimming areas, driftwood, and subdued background colors will help these fish feel secure and look their best.

🐟 Tank Mates

Moenkhausia costae is a peaceful species that fits well in calm community tanks. They’re active but non-aggressive and thrive alongside other peaceful species.

Compatible tank mates:

• Small to medium-sized tetras (e.g., Lemon, Glowlight, Ember)

• Rasboras

• Peaceful gouramis (e.g., Honey Gourami)

• Dwarf cichlids (e.g., Apistogramma, with care)

• Corydoras catfish

• Otocinclus

• Snails and larger freshwater shrimp

Avoid:

• Fin-nippers

• Aggressive or very large fish

• Overly shy species that may be stressed by their activity

Keeping them in a school of 6 or more encourages natural behavior and reduces stress.

🍽️ Feeding Habits

Moenkhausia costae are omnivorous and easy to feed. For optimal health and coloration, offer a varied diet:

• High-quality flake or nano pellet food

• Frozen or live food like brine shrimp, bloodworms, or daphnia

• Crushed freeze-dried tubifex or mysis shrimp

• Supplement occasionally with spirulina-based foods or vegetable flakes

Feed once or twice daily, giving only what they can consume in 2–3 minutes to prevent leftover buildup and maintain water clarity.

🧼 Care and Maintenance

• Perform weekly water changes (25–30%)

• Ensure proper filtration and aeration

• Use a secure lid, as they may jump when startled

• Monitor ammonia, nitrite, and nitrate levels closely

• Add floating plants or hiding spots to help them feel safe

Although not overly delicate, M. costae prefers stable water conditions and good aquarium hygiene to thrive.

🌿 Why Choose the Moenkhausia costae Tetra?

The Moenkhausia costae Tetra is a rare and attractive choice for aquarists looking to add something different to a peaceful community tank. Its sleek appearance, shimmering body, and engaging swimming patterns make it both a visual and behavioral delight. While slightly less common than mainstream tetras, it's equally rewarding for those willing to provide stable care.

Elevate your aquarium with this underappreciated beauty—bring home Moenkhausia costae today!