Betta eggs hatch in about 24-36 hours after spawning. The first few days after hatching the fry survive off of their egg sack and the infusoria in the tank. Infusoria are tiny organisms that will naturally occur in the tank, especially if there are live plants present.
Once the fry become free swimming it is up to you to provide them with food. Free Swimming means that the fry are now able to swim horizontally, and no longer need the help of the male to stay near the top of the water. You can remove the male once the fry are free swimming. You must have live food available for the fry once they are free swimming. They will not eat flake or powdered foods at this stage in their life. Newly hatched live baby brine shrimp (bbs), micro worms, and vinegar eels make great first foods. I feed my fry a small amount of micro-worms and vinegar eels starting on day one of free-swimming. It is very important not to pollute the tank with excess food.
On the fourth or fifth day I also begin feeding small amounts of live baby brine shrimp. The fry should be fed two or three times a day. They should have rounded stomachs which will look white from eating microworms and vinager eels, or orange from eating bbs.
* Be careful not to overfeed bbs, and be careful not to let the unhatched bbs eggs get in the fry tank. Overeating of bbs, and/or eating unhatched eggs can cause swim bladder problems. *
About one week after hatching you should begin cleaning the tank by siphoning out any waste or uneaten food off the bottom. I use airline tubing attached to a small length of rigid airline tubing to do this. You should siphon the water out into a clear cup or jar so that if you happen to suck up any babies you will see them and can return them to the tank. You can return them by gently sucking them up with a dropper and then squeezing it into the tank to release them. You should replace the dirty water with clean water that is the same temp. or a few degrees warmer than the water in the tank. You must pour the water in very slowly, so slowly that it actually is only dripping in. You can siphon the new water in with airline tubing. Week one through three I take out about a half gallon of water, and then add in a little over a half gallon of new water. I do this at least twice a week. Good water quality is one of the most important things in helping fry grow and stay healthy.
Fry can be fed micro-worms and bbs every day until they are about a month old. Then you can begin introducing them to finely ground dry and/or frozen food, a little bit at a time along with the live food. They may not eat it at first, but if you persist they soon will, they are very competitive for food at this age. I feed Mike Reeds NOBS Fry Food and Golden Pearls at this stage of the fry’s life, as well as live bbs once a day, or every other day. After a few more weeks I also begin feeding Hikari Micro Pellets, ground New Life Spectrum, ground cichlid bio-gold, and freeze dried daphnia. You must once again be careful not to pollute the tank with excess food. Dry food will pollute the tank quickly if it is uneaten and left in the tank. If you add dry food and it is not eaten within a couple of hours, siphon it out of the tank and try feeding it again at the next feeding time.
Around 6-10 weeks you will need to begin jarring the males. Some males (or even some females) will get very aggressive towards they’re siblings before this age. You can remove these babies at an earlier age if you are noticing torn fins and/or very aggressive behavior. Some spawns seem to get along better than others, and can be left in the grow out tank for longer than the more aggressive spawns.
When jarring a young Betta you should fill they’re jar up with water from the tank that they have been living in. This will make the process much less stressful for them. Net them very carefully and gently out of the breeding tank and place them in their new home, or you can dip a cup into the tank and catch them with that. It is a good idea to put all they’re jars near each other so that the young Betta can see each other. Newly jarred Betta have the tendency to become depressed for a while after being taken away from they’re siblings. Being able to see each other helps to lessen the depression and stress.
In my opinion newly jarred baby Betta should not be kept in jars that are less than a gallon in size. Jars smaller than a gallon can stunt a young Betta growth, and will not allow him to reach his full potential. The more room the Betta has, the better. The water in the jars should be changed every few days. You must be very careful to make sure the new water put in their jars is the same temperature and pH as the old water.