I’ve Got a New Mouthbrooding Betta – Now What?
By Mike Hellweg

Lately there has been a great influx of wild Betta species, many of which have never been kept in aquaria before. Some of them are even new to science. How is the home aquarist to acquire information on keeping these wonderful animals if no one has kept them before?

Fortunately, especially with the Mouthbrooding Bettas, there are enough generalities between species that a basic sort of “rule book” can be created that will carry the aquarist through the first few weeks. After that, with careful observation and a little time spent taking notes, the home aquarist can become the “expert” on that species! The following is a basic primer on Mouthbrooding Bettas. Each species, and even population of a given species, may have it’s own idiosyncrasies, but in general, there are many things that can be stated in common with most species.

Please note that what follows is “what works for me”. Fish do not read books or articles. Different fish will react differently to different situations. The following are generalizations that I have used in spawning nearly a dozen mouthbrooding species so far.

Why mouthbrooding and what exactly is mouthbrooding?

First, we need to know what mouthbrooding is and why many wild Bettas use it as a breeding strategy. Most people, when they think of Anabantoids in general, and Bettas in particular, think of bubble nests. In fact, the Anabantoids are often all called Bubblenesters! Actually, many species are not bubble-nest builders! The majority of known Betta species are mouthbrooders, and several more are “switch hitters”, using either a small bubble nest or mouthbrooding, whichever the situation warrants!

It is widely believed that in Anabantoids, mouthbrooding behavior evolved from bubble-nest building. A bubble-nest works fine in stagnant water, and is even advantageous – keeping the eggs and developing fry together, safe, and moist while keeping them close to the oxygen-rich atmosphere. When a fish moves into a stream, though, a bubble-nest is very difficult to keep together. Since the male is already manipulating the eggs with his mouth when building a bubble-nest, it is just a short evolutionary hop to keeping the eggs in his mouth all of the time.

In addition, there are other advantages to mouthbrooding. A male bubblenester is tied to the nest and can’t move far from it or he risks loosing the eggs or fry. A male mouthbrooder can move as he needs to in order to keep himself and his brood safe. While he does expend more energy with this reproductive strategy, he also has a greater chance of all or most of his progeny reaching a stage where they can fend for themselves. The awkward and defenseless stage where they would be unable to swim while carrying their yolk sac is avoided. Further, the male is able to keep the eggs well oxygenated by moving a current of water over them with every breath. All around, it is a more efficient reproductive strategy.

What do I feed them?

Mouthbrooding Bettas are mostly “lay-in-wait” type predators. They spend much of their time hiding, or just hanging around large objects in the streams, waiting for a meal to float by. When something tempting floats by, or hits the surface, they go after it, swallow it rapidly, then go back to lurking – waiting for their next meal. Even newly caught wild fish will quickly go after quality flake foods, frozen foods, and pellets. They especially love meaty foods like frozen brine shrimp, bloodworms, and the smaller ones also love frozen Daphnia.

In addition, they will eat any live food that fits in their mouth! They relish worms of all kinds: whiteworms, blackworms, and red worms of appropriate size. The African Dwarf Red Worms that many Killie hobbyists cultivate are just about bite size for most of the larger mouthbrooders. They can be chopped up and fed as chunks to smaller mouthbrooders. Larger Mouthbrooders will also eat smaller fish. Betta unimaculata, in particular, seems to relish tiny fish – including other Bettas! While a newly caught fish might hide and pout for a few days or even a week or so before eating, appropriately sized live worms should persuade them to come out and eat. If you are worried about the worms getting down into the gravel before the fish can find them all, use one of the little plastic worm feeders that allow the worms to slowly wriggle out and drift down one at a time. As soon as the fish learn where they come from, the worms won’t last long! For the most part, once settled in, you don’t have to worry about a Mouthbrooding Betta starving!

To feed your newly released fry, start with live baby brine shrimp, microworms, and vinegar eels. They quickly move up to Grindal worms, and will attack small pellets and flake foods relatively soon after release.

What kind of tank setup is appropriate for Mouthbrooding Bettas?

As with just about any other kind of fish, the larger the tank, the better. I would recommend no smaller than a 10-gallon tank for a pair of smaller Mouthbrooders. For a small group, I wouldn’t use anything smaller than a 20-long. For the larger Bettas I would recommend no smaller than a 30-gallon tank for a pair, and preferably at least a 55 for a small group of them. The good thing is that this tank can serve as both a maintenance tank and a breeding tank.

First of all the tank should be tightly covered. All Bettas are excellent jumpers! They can find the smallest opening and take advantage of it. I once had a group of Betta balunga play “follow the leader”. Over a 6-hour period they all jumped through a small opening about ¼” wide in the cover of the tank. I found them all dried up on the other side of the room, about a foot apart.

What about the water, pH and that sort of thing?

Water conditions seem to be unimportant to Mouthbrooders, at least the ones I’ve worked with so far, regardless of whether they were wild caught or tank raised. As long as you use a drip line to slowly introduce the fish to your water and do regular water changes, pH and hardness should not present any real problems. In fact, you are more likely to stress the fish and cause permanent or even fatal damage by playing with water parameters than by allowing it to get used to your water and maintaining water quality. A wildly fluctuating pH, which can easily happen when you play with the water chemistry, can be deadly. A constant, but slightly elevated pH won’t be. Don’t allow nitrogenous wastes to build up. Do regular water changes, feed them well and the fish will be happy.

What do I need for décor, filtration, and other equipment?

The tank should be setup with a merrily bubbling sponge or power filter (your preference here), but you do want to create some current, though not a raging torrent! I suggest using at least a thin layer of medium to dark natural gravel, just enough to keep the fish from seeing light or reflections coming up from below. If you are going to plant the tank, you’ll need more gravel appropriate to the types of plants you will use. A few large rocks, a big piece of driftwood, and a flower pot laid on it’s side for each female, plus one extra, would complete the scene. The tank can be planted around the perimeter with plants like Vallisneria, Sagittaria, Amazon Swords, or other grass like plants. Add some Water Sprite (Ceratopteris sp.) or Frog Bit (Limnobium sp.) floating on the surface, and you are done. I would stay away from smaller floating plants like Duckweed (Lemna sp.) or Giant Duckweed (Salvinia sp.) just because these plants can become a really annoying pest whenever you work in the tank.

Lighting can be medium (1 – 2 watts per gallon) – just enough for the plants. The Mouthbrooders don’t really seem to care for bright light too much. In medium light, they spend more time out in the open. Don’t bother with a heater. Room temperature will be fine for them. If you are comfortable, they will be too. Add extra aeration, and do extra water changes in the summer time if the temperature goes up into the 80’s F for any length of time. Most of these fish come from cooler, flowing water and don’t tolerate heat very well.

Okay, I’ve got these fish, they’ve settled into their tank, they’re eating, now how do I tell boys from girls?

Sexing some mouthbrooders can be frustrating, especially when they are young. Some of them are unfortunately difficult to sex even as adults. Sometimes you have to wait until they actually get ready to spawn before you are certain you have a pair!

In general, Mouthbrooder males and females are nearly the same size as adults – with the males sometimes being slightly larger. They often share similar coloration, except at breeding time. Males do have larger heads, due to the fact that they must have room to carry the eggs and fry. This can usually be seen relatively early in development. When you look down on young mouthbrooders from above, the young males have more of an upside down ‘U’ shape to the head, while young females have more of an upside down ‘V’ shape.

As they get older, males of many species develop deeper coloration than females – in some species they look very different. Males also often develop extensions on the caudal fin that females generally do not have. In some species, males have more color in their unpaired fins (dorsal, anal, and caudal) than females – some females may even have completely clear fins. Another key is to look at the dorsal fin of young adult and adult fish. In males, the dorsal fin is often only raised when displaying, and while lying against the body it often reaches to or past the base of the caudal. In females, it is usually held erect and in the rare occasion when held close to the body, it does not reach the base of the caudal. Finally, as the eggs ripen, most females will show an egg tube protruding from the vent. This is a small, white nub that is just in front of the anal fin. The tip is round. If the males ever show a tube, it is pointed. I have only actually seen it on male Betta unimaculata, one of the larger mouthbrooders.

I have both sexes – now how do I get them to spawn?

Spawning in all fishes is a natural urge that can be almost overwhelming. All we as aquarists need to do is find the right set of conditions to trigger this urge, and let the fish take it from there. In general, with mouthbrooders it is fairly easy to trigger the urge.

I recommend conditioning your fish for spawning, at least the first time. That involves separating males and females either by moving them to another tank (better) or at least putting a divider in the tank to separate them. Feed them heavily with a mixture of live foods, especially meaty foods like worms, and good quality frozen foods like bloodworms and brine shrimp. Keep them separate for at least a week, then move them back into the maintenance tank or remove the divider. I try to use a group of adults and let them choose their own mates. This seems to work better than forcing a pair to spawn by themselves. There also might be some trigger (hormonal, behavioral, or who knows?) that only a group of adults can provide to get a pair to separate off and spawn.

Another old timer’s trick to trigger a spawn is doing a large water change with slightly cooler water (no more than 5 degrees F or you may stress the fish!). This simulates a heavy rainstorm, and may be all you need to do to trigger a spawning. Many fish in the wild only spawn after the Monsoon season begins, as this will be the time when the most food is available to their fry.

Spawning should occur within a day or so of putting them together or doing the water change. If not, separate them again and recondition them, try different mates if you are only using one pair, or wait a while and try them again – they may not yet be old enough.

Unfortunately, one thing that many aquarists today lack is patience. And that is often the key to getting the fish to spawn. No Mouthbrooder will spawn until they are fully sexually mature. In some species, this may be as early as 6, 8 or 10 months. In other species, they must be a year or two-old before they are fully mature and ready to spawn – even if they have reached adult size. Once you have mature fish that spawn, it is hard to stop them, even after you (and all of your friends – and the local shops) have all of the young you could ever want!

Remember most Mouthbrooders come from streams that are flowing from the highlands. This means COOLER water. I generally use water in the upper-60’s to lower 70’s F. I have never had a spawning in water above 78 degrees F. At temperatures above 80 degrees F, some species are visibly stressed out. Keep the water cooler and you will have a better chance of success.

The fish need a place to spawn that is semi-private. I like to use clay flowerpots turned on their sides – open towards the front. That way I can watch what is going on, and the fish can “hide” in the pots without other fish seeing them from their own pot. For the smaller species I use 4” pots, for the larger species I use 6” pots.

What happens during the actual spawning?

The females generally initiate the spawning, choosing the male whose display, body or fin size, or coloration is most pleasing to them. The female drives away competing females and other males.

Spawning proceeds as with most other Anabantoids, with the male embracing the female inside the flowerpot. They line up their vents and the male fertilizes the eggs as the female releases them. The eggs fall onto his anal fin, which he cups to “catch” the eggs. After he fertilizes them, he releases them and they slowly fall to the bottom, where the female helps him gather them up. Sometimes the male will pick most of the eggs up, but usually the female will spit the eggs at the male, and he will catch them one at a time. When his mouth is full, he will refuse to take any more eggs, even if the female spits them at him repeatedly. Spawning may be interrupted several times as the female chases away any “intruders”. She can often be quite aggressive, and I have found dead females after a spawning. That’s why it’s a good idea to have a few extra flowerpots for the other females to hide in.

How do I know when spawning is over?

When spawning is complete, the male will go off to brood the eggs. In many species, his coloration, especially around the head, will grow much darker. He will hang in a corner, out of the way. Some males hang out near the surface in the floating plants, others hide in a flowerpot. I have seen multiple males hiding in the same “cave”, all mouthing their eggs with only their heads peeking out. Some males will pick at food while brooding; others don’t eat the entire time.

What do I do after they spawn?

Depending on species and temperature, the male will release the fry after a week to 10 days. When trying to save spawns, I will remove the male after about 5 days to his own 5 to 10-gallon tank, set up with water from the main tank, a flowerpot turned on it’s side, some plants and a sponge filter. Most males do not spit the eggs or fry, those that do usually ignore them from that point on. I have not tried to artificially incubate the eggs or fry as is done with Mouthbrooding Cichlids, though I imagine that is possible.

Once the fry have reached maturity, the male will release them. Most of the fry head for the bottom of the tank, though with the size of many broods, fry can be found all over. After a day or so, many will be found near the surface. I remove the male as soon as he releases the fry – he might consider them as food and he has not eaten for several days! I put him back in the main tank, placing him in a large net breeder filled with plants for the first couple of days to allow him to get some food and some rest. After a couple of days, I release him back into the main tank. The fry are immediately fed as outlined above. They grow quickly, some more quickly than others. The larger fry will eat their smaller siblings, so you do need to do some grading for size as time goes on.

Smaller Mouthbrooding Species (up to 3”): Betta albimarginata, B. channoides, B. dimidiata, B. foerschi, B. picta, B. simplex, B. strohi

Larger Mouthbrooding Species (over 3”): Betta akarensis, B. anabantoides, B. balunga, B. breviobesus, B. chini, B. chloropharynx, B. climacura, B. edithae, B. enisae, B. fusca, B. hipposideros, B. macropthalma, B. macrostoma, B. ocellata, B. patoti, B. pi, B. prima, B. pugnax, B. pulchra, B. renata, B. schalleri, B. spilotogena, B. taeniata, B. tomi, B. unimaculata, B. waseri

Reported Potential Switch Hitters: Betta brownorum, B. coccina, B. rutilans