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