Tank Size and Setup for Killifish
Killifish are small, active fish that do best in tanks of at least 10 gallons for a small group. For a single pair or small species, a 10-gallon tank works well. Larger species or groups need 20 gallons or more. Provide a tight-fitting lid because killifish are excellent jumpers. They prefer a well-planted tank with soft, acidic water (pH 6.0-7.0, hardness 4-8 dGH). Use dark substrate like peat or sand, and add floating plants to diffuse lighting. A sponge filter is ideal to avoid strong currents. Keep temperature between 72-78°F (22-26°C) for most species, but always check your specific species’ needs.
Diet and Feeding
Killifish are carnivorous and need a protein-rich diet. They thrive on live or frozen foods such as brine shrimp, daphnia, bloodworms, and mosquito larvae. High-quality flake or pellet foods can supplement but should not be the staple. Feed small amounts once or twice daily, only what they can eat in a few minutes. Avoid overfeeding to prevent water quality issues. Some species are picky and may refuse dry foods, so be prepared to offer live foods regularly.
Tank Mates for Killifish
Killifish are generally peaceful but can be timid. Good tank mates include small, non-aggressive fish like neon tetras, ember tetras, pygmy corydoras, and small rasboras. Avoid large or fin-nipping fish like barbs or cichlids. Also avoid very fast or boisterous species that outcompete killifish for food. In a community tank, keep only one male per tank to prevent aggression. Some species are best kept in a species-only setup, especially annual killifish. Always research your specific killifish species before adding tank mates.
Water Quality and Maintenance
Killifish are sensitive to poor water conditions. Perform weekly water changes of 20-30% with dechlorinated water. Test water regularly for ammonia, nitrite, and nitrate. Use a mature filter to maintain biological balance. Avoid sudden changes in water parameters. If your killifish show signs of stress like clamped fins or rapid breathing, check water quality immediately. For any health issues, consult a licensed veterinarian for diagnosis and treatment.
Breeding Killifish
Many killifish are easy to breed. Provide spawning mops (yarn mops) or fine-leaved plants for egg deposition. Separate adult fish after spawning to prevent egg eating. Some species are annual, laying eggs that require a dry incubation period. For non-annual species, eggs hatch in 10-14 days. Raise fry on infusoria or microworms, then gradually move to baby brine shrimp. A separate breeding tank with soft, acidic water increases success.
Key Takeaway
Provide a 10+ gallon planted tank with a tight lid, feed live/frozen foods, and keep peaceful tank mates to ensure healthy, colorful killifish.