Betta pre-spawning behavior
The male will build a bubble nest. Bubble nests can be large or small; covering the entire top of the aquarium or not much larger than a grapefruit. If something is floating on the water, like a leaf, the male will usually build his bubble nest under it.
You can prompt a reluctant male to build a bubble nest simply by floating a plant on the surface. Many breeders use plastic lids (thoroughly cleaned, of course) to float on the water. Anything can be used, so long as it floats, though research suggests that round items that are yellow and about the size of a grapefruit work best. This may be because they look a bit like the large floating leaves of the bettas wild environment.
When to put the male and female together
The male will flirt with the female in between working on the bubble nest. He will flare, swish his tail and bend his body back and forth.
When the female is ready she will have dark vertical bands on the side of her body and will position herself so that males can see the bands.
Once the fish are together, there may be quite a bit of aggressiveness on the part of the male, or the female, or both. They will nip at each other, and the female may decide to retreat. It’s a good idea to give her a place to hide every once and awhile. Sometimes a male will be so aggressive, that he will kill his prospective mate. Keep an eye on your pair to make sure they are not mismatched at this critical time.
After anywhere from a few rounds of this to a few days later, a receptive female will eventually follow the male under the bubble nest, where the actual spawning will happen.
Betta Spawning Behavior
After all the preparation, the fish are actually spawning when the male wraps his body around the females and appears to squeeze the eggs out of her. The male will turn on his side and bend his head and tail into a U shape while the female turns upside down and “lies” into this u shape. The fish will be at cross angles in this position, but their vents are very close so the eggs from the female and the milt from the male merge together.
Each embrace lasts about 15 seconds. There are many embraces, and the first few may not result in any eggs being released by the female. After a few tries, some eggs will come out. At the height of spawning, each squeeze may release 20 or more eggs. It is rare, but occasionally betta fish have up to 1000 fry in a spawn. Expect more like 500 to be average.
After each batch of eggs is released the female may appear paralyzed – and she in fact is. The male will be hurrying down to catch the descending eggs, then put the fertilized eggs into the bubble nest, where they will stay (mostly, he’ll put whatever ones fall outback) until they hatch about two days later.
After spawning the male starts working on his bubble nest again. He may create an entirely new bubble nest and move the eggs to it, or he may just keep working on the nest. It’s fairly rare, but not unheard of, for a male to eat some of the eggs. Females are much more likely to eat the eggs.
The male betta is also likely to become aggressive to the female. In some pairs, this aggression may come out even before all the eggs have been released. You need to keep a close eye to get the female out of the tank before the male becomes too aggressive. At the very least, the female will need a safe place to hide away from the male until you can remove her.
Females need about a week of rest in 80-degree water before they can spawn again. Males can spawn up to twice a day, but the spawn will probably be larger if the males are given a few days rest in between, too.
Egg Hatching & When to Remove the Male Betta
The fry will hatch 1.5 to 2 days after spawning. After hatching the tiny fry can’t do much more than wiggle, and they frequently wiggle their way out of the bubble nest. The male has a busy job for the next few days putting the fry back in the bubble nest and maintaining the nest. It’s a 24-hour job, and if the male misses any of the fallen fries, they may not survive.
It is best not to try to do the male betta’s job for him. Even if you lose a few of the newly born fry, trying to save them will probably disrupt the tank and the nest, and really upset your male betta. It’s better to just leave them alone.
When to remove the male
Two days after hatching the fry have figured out a bit of how to swim. They will leave the bubble nest and spread out over the tank lying just under the water surface. The male, having not eaten in all this time, may start eating some of the fries. This doesn’t always happen, but as before, keep a close eye on the breeding tank to make sure all is well. Many breeders will remove the male at this point, as he’s done his job and can’t really help the fry anymore.
Move the male to a nice warm, clean tank with no other fish in it. Feed him top-quality food and be good to him for at least a week as he recovers from raising his fry.
This is a very tough part of breeding bettas, and a very good reason not to breed them in the first place.
With each average betta spawn being 500 young fish, even modest culling means you’ll be killing 250 little betta youngsters. Even keeping 250 is difficult, because you’re going to have to house, feed and clean 250 bettas. If you know of the community event that needs party favors or tokens, you might be able to unload a couple of dozen of your bettas there.
If possible, arrange for at least 50 new betta homes before you breed your fish unless
a) you don’t mind killing off 90% of a spawn
b) you have a very, very large fish room
c) you have a standing arrangement to sell the fish to a retail vendor
Assuming the spawn (the group of baby bettas resulting from your breeding effort, or, more precisely, your fishes’ breeding effort) is about 500 fish, and assuming you can’t possibly keep more than 200 of those fish, you’re going to have to kill, or “cull” 300 fish.
To do this, you’ll first need to separate out which ones you want to keep, and which ones you don’t. For the purposes of this example, I’m going to assume all your spawn were raised together, so they can continue to be kept in the same tank.
Get two large containers. One will be for the fish you want to keep, the other for the fish you don’t want to keep. If you’re a softie like me, you may want a third tank for the fish you aren’t sure about.
Get a good light, and if necessary a magnifier glass. Get a container where you can very, very closely see each fish. You’re going to give each of those 500 fish a close once-over to weed out the losers.
The first cull can be to get rid of the sick and clearly malformed fish. These should be the ones that are clearly not nature’s favorites, and hopefully putting these guys in the cull tank won’t hurt too much. Remember – in the wild, barely in one five would survive anyway. You’ll probably lose 10-15% of your spawn in this cull.
The next cull can be to remove fish with undesirable colors and even modestly malformed fins or other body parts.
The third cull can be to weed out the remaining fish that are nice but that you just don’t have room for. This will be the hardest cut. This is when it might be good to think of local pet stores, local teachers… anyone who might be able to find homes for even some of these perfectly good fish that just quite up to your breeding standards.
To actually kill the culled fish, get a bucket and fill it half with water and a half with ice cubes. The water should be extremely cold… almost cold enough to freeze on the top. Then net the to-be-culled fish and drop them, batch by batch, into the icy water. This is the easiest and most humane way to kill them. The fish will go into shock upon contact with the water, and they will be knocked out in a second or two. They won’t feel the rest. At least that’s what the medical information says.
Feeding – micro worms and baby brine shrimp
Fry needs to be fed constantly. This is their primary need at this critical time. And it’s hard to feed them compared to feeding adult fish because they are so tiny that most food won’t fit in their mouths.
Most breeders feed new fry freshly hatched brine shrimp. You’ll need to have your brine shrimp hatching timed to about a day or two after your fry has hatched. This means you’ll probably need to get your brine shrimp culture started about the same time you are setting up the spawning tank.
Other breeders feed the newborn fry protozoans that they’ve cultured from protozoan starter cultures. You can buy these from biological supply stores or from fish supply stores online. To get the start kit started, put it in water will some food, such as a dried vegetable and a very small pinch of betta food pellets.
It’s hard to maintain the water in a fry tank. You need to get the water out, but keep the tiny fry in. Many breeders use turkey basters or siphons to carefully get the water out, then replace it with clean water. Because there is so much food in the water, it gets dirty fast, and fry must have clean water for optimal growth and to prevent disease. An outbreak of disease can wipe out a whole spawn in a matter of days, so the water changes, no matter how much of a hassle they are, are essential.
Some fry will grow faster and larger than their siblings. Within a few weeks of hatching, some of them may become so aggressive that they need to be separated. Even if they are not aggressive, the largest fish should be moved to a special tank where they can all get big together, without overpowering and hogging food from their smaller, but possibly just as valuable, sisters and brothers.
Fry raised together will not fight. But if they are separated at any time, upon reunion, they’ll fight as they’ve never met each other.