Feeding the fry is something that is often overlooked in the excitement to get a first spawn. You can have lots of healthy free-swimming babies but if you do not feed them correctly they will die quickly.
What to Feed?
This really is personal preference but there are a few options.
Powdered Fry Foods
Bettas are carnivores and many of the fry will not choose to eat this. If you have a very large spawn, it is one way to lower your numbers to a more manageable number. Personally I don’t like that method of culling since you might lose some of the best fish this way.
These live a long time and are a great first fry food. No matter how many different methods I have read about harvesting them, I still have trouble doing it so do not use these very often. Still if you want to try them, they are a great first food. You can read more about them on the Basement Betta’s Blog.
Liquid Fry Food (Liquifry no. 1)
This is my preference to use for the first couple of days but it has become difficult to find and seems to be only available on Amazon.com currently.
Once the fry are freeswiming I add 3-5 drops (depends on whether it is a few fry or hundreds) to a cup of aquarium water, swirl to break up any chunks and pour in 2-3 times a day. DO NOT feed more of the liquifry until the water clears. Overfeeding this food will kill your fry. Most liquid fry foods are made up primarily of egg yolk. You can also boil an egg, squeeze through a handkerchief and feed a few drops of this. I have not tried this but from what I have read most betta fry will eat it readily and the particles are small enough for them. If over fed, egg yolk will kill the fry in short order and many breeders DO NOT use it for this reason. If the liquifry is unavailable or too expensive, go ahead and use tiny worms.
I have used microworms, banana worms and walter worms with success. Banana and walter worms are smaller and therefore better first food than microworms. Walter worms are half the size of microworms and banana worms are half the size of walter worms. The easiest way to get the smallest worms is to take a q-tip and wipe some off the culture container wall and swish in a small clear container of water. The bigger worms sink the fastest leaving the younger, smaller worms suspended longer. A syringe without a needle, eye dropper or pippette works well to suck up the worms and squirt a small amount in the aquarium. DO NOT add more worms if there are still some on the bottom of your aquarium. I usually add a ramshorn or mystery snail to each fry aquarium because they will eat dead fry and dead worms or baby brine shrimp. It is much easier to siphon out a little snail poop than have to try to siphon every inch of the aquarium bottom (siphoning at all is a pain because there is a good chance you will suck up babies). I cannot emphasize this enough. DO NOT over feed. It is much better to feed a few times each day with very small portions and have the fry eat everything in between feedings.
Baby Brine Shrimp
This is one of those foods that can also be used to reduce your spawn size. If you choose to feed it before the fry are about a week old, some of the babies just won’t be able to eat them. I start feeding baby brine shrimp at a week of age once a day and feed walter or banana worms most of the time for a second feeding. I also sometimes add Vitachem to a small dish of water with worms or bbs for a few minutes before feeding to make them more nutritious.
Important: betta fry can develop swim bladder problems that cannot be cured if allowed to gorge themselves on baby brine shrimp (so don’t put so much in that they can munch for hours on end). Just feed the amount they can consume in 3-5 minutes. If you want to feed more, feed small feedings a few times a day rather than a large amount all at once. If your betta fry cannot raise their back ends in the water, this is a permanent condition with no cure. Feed baby brine shrimp in small amounts to avoid this issue. Betta fry that develop swim bladder issues where they float, might be cured but it involves time and feeding smaller amounts and a diet change (at least for awhile).
At around 4-5 weeks of age I introduce very pellets and small amounts of freeze dried foods like artctic copopods. The babies still get some worms and baby brine shrimp until they are too large to show interest in them.
Once in jars the main food is new life spectrum .5mm pellets for a couple of weeks. When they are arund 3 months old I start feeding the larger adult NLS betta pellets or sometimes just the thera A 1mm pellets since it does seem to help prevent velvet outbreaks. Supplemental foods are frozen (thawed) daphnia or baby brine shrimp. I hope to start raising live daphnia soon but have not tried that yet.
Note: Bettas really are not made to eat dry foods and too many pellets at once can cause swim bladder problems or constipation. A betta’s stomach is about the size of it’s eye so feed accordingly. If you want your bettas to have more food, increase the number of feedings rather than number of pellets.
If your betta starts to float, you can try feeding him a frozen thawed piece of pea (just break off a very tiny piece). It is more often males than females that float after consuming pellets. The pea will often push the air and pellets through the betta’s system.