How to raise fry: water quality, food and stress

Water quality

Fry are sensitive to ammonia, nitrite, and sudden parameter swings. Keep ammonia and nitrite at zero. Nitrate should stay low (under 20 ppm is ideal). Do small, frequent water changes (e.g. 10–20% every few days) rather than big ones — large changes can shock fry. Match temperature and dechlorinate new water. A cycled, mature tank is essential. If you use a fry tank, cycle it first or use media from an established filter.

Food

Fry need tiny, frequent meals. Their mouths are small and their metabolism is high.

• Livebearer fry (guppy, platy, molly): Big enough to eat powdered food, crushed flakes, or baby brine shrimp from day one. Feed 3–5 times daily in small amounts.
• Egg-layer fry (tetras, cichlids, etc.): Often need infusoria, microworms, or liquid fry food at first. As they grow, move to baby brine shrimp, powdered food, and crushed flakes.

Remove uneaten food within a few minutes. Rotting food spikes ammonia and harms fry. See frozen food — if using frozen, defrost and use only a tiny amount.

Stress

• Predation: Adults (including parents) will eat fry. Use a breeding box, fry net, or separate fry tank. Dense plants (java moss, guppy grass) give hiding spots in a community tank but won’t save all fry.
• Flow: Strong filter intakes can suck up fry. Cover intakes with sponge or mesh.
• Handling: Minimise netting and moving. If you must move fry, use a gentle method (e.g. a cup) and match water.
• Light and noise: Sudden changes can stress fry. Keep the tank in a calm spot.

Fry tank vs community tank

A dedicated fry tank gives the best survival: no predators, controlled feeding, and easier water management. In a community tank, expect losses — plants and hiding spots help, but some fry will be eaten. It’s a trade-off between convenience and survival rate.

Quick takeaways

• Keep ammonia and nitrite at zero; do small, frequent water changes.
• Feed tiny amounts 3–5 times daily. Remove uneaten food quickly.
• Protect fry from adults (breeding box or separate tank); cover filter intakes.