The Cynolebias constanceae is a rare and striking annual killifish species native to South America, particularly the seasonal freshwater pools of Brazil and Uruguay. With their bold patterns, deep coloration, and unique biological life cycle, these fish are a fascinating choice for aquarists seeking something truly different.

Reaching 3–4cm in length, Cynolebias constanceae is part of the Rivulidae family and known for its short but vibrant life. Like most annual killifish, this species hatches from eggs laid in the substrate, grows rapidly, breeds, and lives out its full life cycle in under a year in the wild. However, in aquariums, with proper care and breeding techniques, the species can be maintained across generations.

🐠 Key Features:

• Scientific Name: Cynolebias constanceae

• Common Name: Constancea Killifish

• Size: 3–4cm (adult)

• Lifespan: 6–12 months (can vary in aquariums)

• Temperament: Peaceful, breeding-focused

• Difficulty Level: Moderate to Advanced

• Origin: Brazil, Uruguay (South American seasonal wetlands)

• Best kept in species-only breeding tanks

🌊 Water Conditions

This species thrives in warm, soft water with minimal flow and a naturalistic setup that mimics seasonal ponds.

• Temperature: 22–26°C (72–79°F)

• pH: 6.0–7.0

• Hardness: 1–8 dGH

• Tank Size: 10+ gallons

• Water Type: Freshwater

• Filtration: Gentle sponge filter preferred

• Lighting: Low to moderate

Provide peat or coco fiber substrate, as this is where they lay eggs. A temporary or simulated dry season is often needed for hatching success.

🐟 Tank Mates

Not recommended for community tanks. Cynolebias constanceae is best kept in species-only setups, especially for breeding.

Why?

• They have a short lifespan and specific reproductive needs

• They may stress or be outcompeted by more active fish

• Their breeding method relies on substrate, which should not be disturbed

🍽️ Feeding Habits

As micropredators, they prefer small, live or frozen foods.

Ideal diet includes:

• Baby brine shrimp

• Daphnia, microworms, grindal worms

• Frozen bloodworms or cyclops

• Soft micro pellets (optional)

Feed once or twice daily, focusing on high-protein items that promote rapid growth and breeding condition.

🧼 Care and Breeding Tips

Cynolebias constanceae are annual breeders, meaning their natural life cycle is tied to seasonal rain and drought.

✅ Breeding Care Includes:

• Provide peat moss substrate or spawning trays

• Allow egg-laying in substrate for 2–4 weeks

• Remove and dry the substrate slightly (in a bag) for 2–3 months

• Re-wet substrate in a separate tank to hatch the fry

• Feed fry with infusoria and baby brine shrimp

Weekly water changes (20–25%) and gentle handling of the substrate and fry are essential.

🌿 Why Choose Cynolebias constanceae?

The Cynolebias constanceae is ideal for aquarists looking for rare, short-lived but rewarding breeding projects. Their brilliant colors, fascinating life cycle, and adaptability to controlled seasonal environments make them a favorite among killifish collectors and breeders.

Add a unique challenge and experience the full cycle of nature—explore the world of Cynolebias constanceae today!