FAQ: Food for fish

Daphnia are small freshwater crustaceans whose shells are rich in fibre. They aid digestion, so they are often recommended for goldfish and bettas prone to constipation.

Mysis are small shrimp-like crustaceans rich in protein and fatty acids. They suit medium and larger freshwater and marine fish, especially picky or predatory ones.

Freezing reduces the risk but does not eliminate it, so buy good-quality food that has been kept frozen from a reliable source. Do not use food that has thawed and been refrozen.

Fine frozen food such as cyclops, baby brine shrimp or crushed daphnia suits fry that have grown a little. Newly hatched fry usually need even smaller food, such as infusoria or fry powder.

Live food triggers natural hunting behaviour, suits picky fish and helps condition them for spawning. But it can bring parasites or disease into the tank, so buy it from reliable sources.

Daphnia or larvae caught in natural waters can carry parasites, pathogens or predatory insect larvae. If you still collect your own, take them only from clean waters with no fish and sort them carefully.

Brine shrimp eggs are incubated in salt water with an air pump and light, and the nauplii hatch within 1–2 days at about 25–28 °C. Strain them and rinse in fresh water before feeding.

Chopped earthworms from clean, untreated soil are a nutritious treat for many larger aquarium and pond fish. Before feeding, keep them in a clean container for a while to empty their gut, and do not collect them where pesticides have been used.

Microworms are tiny nematodes that are easy to culture at home on oatmeal. They are used as a first food for fry, because they stay alive in water for a long time and sink to the bottom.

Infusoria are microscopic single-celled organisms used to feed very small fry, such as betta or gourami fry. They can be cultured in a jar of water with plant matter, or ready-made liquid fry foods can be used.

Live feeder fish, especially goldfish, often carry disease and parasites and may contain substances that harm predatory fish over time. Most predators can be trained onto frozen food or pellets.

Live food such as tubifex or bloodworms is kept cool, often in the fridge, in a shallow container of clean water that is changed regularly. It only lasts a few days, so buy only as much as the fish will eat.

Tubifex often live in polluted water, so live ones can carry bacteria and parasites. Frozen or freeze-dried tubifex are safer, and live ones need lengthy rinsing in clean water.

Pond fish naturally find insect larvae, worms and small crustaceans, so live food is not essential for them. Earthworms or daphnia can be given now and then, especially in spring when the fish are recovering after winter.

Daphnia are kept in a large container or bucket of unchlorinated water in a bright but not hot spot and fed yeast or green, algae-rich water. They multiply quickly in the warm season, and growth slows in the cool season.

Mosquito larvae from a clean rain barrel are nutritious fish food, but give only as many as the fish will eat at once. Otherwise the hatched mosquitoes will be flying around your home.

It is freeze-dried bloodworms, brine shrimp, daphnia or krill with the water removed but most nutrients kept. It keeps for a long time at room temperature and is a convenient alternative to frozen food.

It is advisable, because dry food swells in the fish’s stomach and can cause digestive problems or bloating. Soak it in tank water for a few minutes until it softens.

Frozen food is moist and closer to natural prey, but it must be kept in the freezer and thawed. Freeze-dried food is stored in a cupboard and is more convenient, but some fish eat it less eagerly.

Not recommended. Freeze-dried food is usually a single ingredient, so it is not complete; it is best given as a supplement to a balanced staple food.