Short answer: Newly hatched betta fry live off their egg sac for the first day or two, then need tiny live foods. The best homemade options are infusoria for the first days, then vinegar eels and freshly hatched baby brine shrimp, moving to microworms or finely crushed food as they grow. Feed small amounts several times a day and keep the water clean.
Why live food works for fry
Betta fry have tiny mouths and are triggered to eat by movement. Moving prey lets them find food and gives them the protein they need to grow. Dry flakes are usually too big and too still for the first week or two.
Infusoria for the first days
Infusoria is the name for the microscopic organisms that grow in water with decaying plant matter. A common home method is to leave a jar of aquarium water with a few blanched lettuce leaves or dried plant material in a warm, lit spot until the water turns slightly cloudy, which usually takes several days to a couple of weeks. Add a small amount of the cloudy water to the fry container. It is a gentle starter food, but the amount of food it provides is small, so most keepers move on quickly. See what to feed newly hatched betta fry for the earliest days.
Vinegar eels
Vinegar eels are tiny nematodes grown in apple cider vinegar and water with a starter culture. They survive in fresh water for hours, so they will not foul the tank the way some foods do. To harvest them, plug the neck of the culture bottle with filter floss, add dechlorinated water above it, and the worms wriggle up into the clear water, where you can siphon them out. They are a good stopgap food but are less nutritious than brine shrimp.
Baby brine shrimp
Freshly hatched baby brine shrimp, or nauplii, are the standard growing food for betta fry. You hatch the eggs in salt water with aeration and warmth for about a day, rinse the nauplii, and feed them in small amounts. Their size is right for fry within the first week or two, and they are rich in protein. Remove or siphon out uneaten shrimp that remain after a few hours. Our betta fry feeding chart shows how to plan feedings by age.
Microworms, grindal worms and blackworms
As fry grow, microworms are a simple culture to keep, and grindal worms are a larger step up. Chopped blackworms can be offered later still. Grindal worms are grown in a ventilated container with moist substrate such as peat or coco coir, and they are fed with small amounts of dry food. These foods suit slightly older fry.
A rough feeding timeline
For the first one to two days, fry feed from the yolk sac. After that, offer infusoria or vinegar eels, then baby brine shrimp from about the end of the first week. At roughly three to four weeks you can add microworms and finely crushed pellets, and by two months most fry can eat small pellets and frozen foods. Growth rates vary, so watch their mouth size and round bellies rather than strict dates. For ideas on picking good foods, read the best food for betta fry.
Keeping the water clean
Fry produce waste quickly, and extra food rots. Feed only what they finish within a few minutes, siphon uneaten food, and do small, frequent water changes with dechlorinated, temperature-matched water. Overfeeding is a common cause of fry loss.
Bottom Line
Start betta fry on infusoria or vinegar eels, switch to freshly hatched baby brine shrimp as soon as they can swallow them, and add worms and crushed foods as they grow. Feed small amounts several times a day and keep the water clean.
