I’ve Got a New Mouthbrooding
Betta – Now What?
By Mike Hellweg
Lately there has been a great influx of wild
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
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
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
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
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
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
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
What do I need for décor, filtration, and other
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
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
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
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
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
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
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.
Reported Potential Switch Hitters: Betta
brownorum, B. coccina, B. rutilans