Feeding Fish Fry

First foods for fish fry, from infusoria and vinegar eels to baby brine shrimp and powdered foods, matched to fry size and fed several times a day.

Why fry need special foods

In the wild, most baby fish eat microorganisms such as protozoans and invertebrate larvae. Because fry have tiny mouths and small stomach capacity, the food must be matched to their size, and they must be fed often. Many keepers feed fry at least three to five times a day.

Infusoria

Infusoria is the term for freshwater microorganisms, including protozoans and invertebrate larvae, that range roughly between 20 and 300 microns. A culture can be started by adding organic matter such as a banana peel or catappa leaf to old tank water and keeping it warm, around 78 to 80 degrees Fahrenheit (26 to 27 degrees Celsius). Infusoria suits the tiny fry of egg-layers such as killifish, rainbowfish, and tetras.

Vinegar eels and microworms

Vinegar eels are harmless white roundworms, around 50 microns in diameter and 1 to 2 mm long, that can survive in fresh water for several days, making them convenient for the smallest fry. Microworms are slightly larger than vinegar eels but smaller than brine shrimp, bridging the gap as fry grow.

Baby brine shrimp

Newly hatched brine shrimp, often abbreviated BBS, measure about 400 to 500 microns and carry a nutrient-packed yolk sac rich in fats and proteins. They hatch in salt water in 18 to 36 hours at 74 to 82 degrees Fahrenheit (23 to 28 degrees Celsius). They suit larger fry such as livebearers, while the smallest egg-layer fry need starter foods for a couple of weeks first.

Powdered foods

Commercial powdered fry foods are available across a wide size range, roughly 5 to 800 microns depending on the product, allowing a keeper to select a grade suited to the fry. They offer a convenient prepared option alongside live foods. Green water, made up mainly of microalgae and phytoplankton, falls in a similar size range to infusoria and can be cultured as an additional first food for very small fry.

Feeding frequency

Because of their small stomach capacity, fry should be fed small amounts at least three to five times a day. Frequent small meals support steady growth while limiting the leftover food that would otherwise foul the rearing water.