How to Raise Fish Fry: Feeding and Care for the First 30 Days

The first month of a fish fry’s life determines everything — survival rate, growth speed and long-term health. Whether you are breeding guppies, bettas or cichlids, this raise fish fry first 30 days guide gives you a clear feeding schedule, water-quality targets and troubleshooting advice drawn from over 20 years of breeding experience at Gensou Aquascaping Singapore. Get these four weeks right and the rest is straightforward.

Days 1–3: Yolk Sac Absorption

Most newly hatched fry carry a yolk sac that supplies nutrients for the first two to three days. During this stage, fry are largely immobile and do not need external food. Resist the urge to feed — uneaten food will foul the water in a small tank faster than you expect, especially in Singapore’s 28–30 °C ambient temperatures where bacteria multiply rapidly.

Keep the lights dim, the filter flow minimal and the tank covered. A sponge filter on its lowest setting protects tiny fry from being sucked in while maintaining gentle circulation.

Days 3–7: First Feeds

Once fry are free-swimming, their mouths are often too small for anything except infusoria, vinegar eels or commercially prepared liquid fry food. Feed two to three times daily in small amounts. If you culture infusoria at home — a jar of tank water with a few crushed lettuce leaves left in indirect sunlight for three days — you will have a reliable supply at virtually no cost.

Freshly hatched baby brine shrimp (BBS) can be introduced from day five for species with slightly larger mouths, such as cichlid and livebearer fry. BBS is the single best live food for accelerating early growth, and hatchery kits are available at most local fish shops for under $15.

Days 7–14: Rapid Growth Phase

By the end of week one, most fry double in size and become noticeably more active. Transition fully to BBS, microworms or a combination of both, feeding three to four times per day. Smaller, more frequent meals keep ammonia levels manageable while ensuring fry always have food in their bellies.

Perform 10–15 per cent water changes daily using aged, dechlorinated PUB tap water matched to the tank temperature. Singapore’s tap water is soft and slightly acidic, which suits most tropical fry, but always treat it with a dechlorinator that neutralises chloramine — standard chlorine removers are not sufficient.

Days 14–21: Introducing Prepared Foods

At two weeks, begin weaning fry onto finely crushed flake or powdered fry food alongside live feeds. This transition is important because a diet of live food alone becomes impractical as the fry grow and their appetites increase. Mix crushed flake with a small amount of tank water to form a paste, then distribute it across the surface so every fry gets a share.

Growth rates vary by species. Guppy fry may already show faint colour at this stage, while betta fry remain translucent. Cichlid fry such as convicts are typically large enough to accept micro pellets by day 18–20.

Days 21–30: Sorting and Grow-Out

By the third week, size differences within a batch become obvious. Larger fry may prey on or outcompete smaller siblings, so separate runts into a dedicated grow-out tank if possible. A 20-litre container with a sponge filter is sufficient for a small group. In HDB flats where space is tight, stackable plastic tubs on a shelving unit work well for this purpose.

Increase water changes to 20–25 per cent daily and feed a varied diet: BBS, crushed pellets, microworms and spirulina powder. Fry that receive diverse nutrition in the first 30 days develop stronger immune systems and more vibrant colouration as adults.

Water Quality Essentials for Fry Tanks

Ammonia and nitrite must stay at zero — fry are far more sensitive to these toxins than adult fish. Test every two to three days with a liquid test kit. Nitrate should remain below 20 ppm. If you struggle to maintain these levels, reduce feeding slightly and increase water-change frequency rather than adding chemical treatments.

Temperature stability matters more than hitting an exact number. Aim for 26–28 °C and avoid fluctuations greater than one degree within a 24-hour period. In air-conditioned rooms in Singapore, a small 25-watt heater provides a reliable buffer.

Common Fry-Rearing Mistakes

Overfeeding is the top killer — cloudy water and a biofilm on the surface are warning signs. Underfilling the tank is another frequent error; a shallow water level helps labyrinth-fish fry access the surface, but egg-layer fry benefit from a normal water depth of 15–20 cm. Finally, skipping water changes because the tank “looks clean” is risky. Dissolved waste is invisible but deadly at fry concentrations.

Related Reading

Guppy Genetics and Colour Inheritance: Selective Breeding Explained

Betta Breeding Complete Guide: Bubble Nests, Spawning and Fry

How to Breed Convict Cichlids: Beginner’s Guide