A New Generation of Betta enisae:
or Breeding the "Metamorphosis
by SUSAN PRIEST
Greater City Aquarium Society, October 2001
Metamorphosis: A striking change of appearance, character, form,
etc. - a transformation.
In nature, the classic example of metamorphosis is, of course, a
butterfly. It starts its life as a caterpillar. Slowly, silently,
and out of sight of the world, each caterpillar cell differentiates
into an antennae, a thorax, or a wing that has been decorated by the
paint brush of an angel. Something no less dramatic than that
happened right under my nose.
This extraordinary story begins, as is most often the case, with
some very ordinary circumstances. For the past two years there has
been a two and one half gallon aquarium unobtrusively holding the
end spot in a row of similarly sized tanks along the top shelf of
the hutch in my kitchen. It has been the home of a pair of Betta
enisae; a mouthbrooding anabantoid native to Borneo. These fish
were drab and unremarkable. For a very long time I didn't even
realize there were two fish in this tank. It was a rare event to see
even one of them. They liked to wedge themselves behind and/or under
the triangular-shaped sponge filter in the rear left hand corner.
Many an observer saw nothing but an empty tank.
Before I plunge into my story I want to answer some questions that
you may be asking yourselves. First, "what is an anabantoid?" An
anabantoid is a fish which has adapted to its oxygen-poor
environment by developing a labyrinth organ. This organ is an
auxiliary to the gills. It allows the fish to extract oxygen from
the air as well as the water.
Second, "what is a mouthbrooder?" A mouthbrooder is a fish which
lays eggs (as opposed to a livebearer which gives birth to viable
fry). What sets it apart from other egg-laying fishes is that after
the eggs are laid, one of the parents (in the case of Betta
enisae, it is the male), "carries" or "holds" the fertilized
eggs within its mouth, usually for several days. This provides the
eggs with an extraordinarily protective environment, and also makes
for small families (at least by fish standards). After the eggs
hatch, the fry emerge, curious and even hungrier than their dad, who
hasn't eaten the entire time he has been brooding them.
This behavior is not unique to anabantoids. Other species, notably
some of the cichlids, are also mouthbrooders. Among fish who
mouthbrood, it is more common for the female to perform the chore of
brooding the eggs.
Third and last, "where in the world is Borneo?" Borneo is part of
the Greater Sunda Islands of Indonesia. It is neighbored on the
south by Java, on the west by Sumatra, on the northwest by Vietnam,
on the northeast by the Philippine Islands, and on the east by
NOW - back to our adventure!
Here's Lookin At Ya
The Betta enisae are regularly fed adult brine shrimp. One
day, at feeding time, Al saw a "brine shrimp" with eyes looking out
at him. You guessed it! Either it took these fish two years to reach
sexual maturity, or they had been waiting for the heat wave of 2001.
This was a Sunday.
We moved the parents to another two and one half gallon tank in the
same row, with a Java Fern, a columnar-shape sponge filter, and
something they hadn't had before - a cave! (It looks kind of like a
water-logged hollow tree that was abandoned by the Keebler Elves!)
This cave was very much to their liking, and they immediately moved
in. They didn't seem to know or care that we could now look in on
Some time on Thursday, we discovered a clutch of "small fry," that
is, a second spawning. These fish were clearly smaller than the
We were spending a lot of time observing and tending both "families"
when the metamorphosis of the title occurred. Both adults were
swimming out in the open, and displaying their brilliant spawning
colors. They were astonishing not only for their beauty, but because
we had never seen both of them swimming together without a trace of
timidity. They were proud to show their true colors. The fact that
we were close by, and so was our camera, did not spook them at all.
Au contraire! They weren't exactly showing off, but they were
doing what comes naturally, and didn't care who was watching. This
was the second Sunday. What followed were several hours of one of
the most fascinating experiences in my ten years of fish keeping.
The pair circled around and around each other. As the circle closed
into an embrace, and the female was squeezed ever so gently in just
the right spot, an egg or two could be seen cradled in the slightly
cupped anal fin of the male, where it was surely being fertilized.
It was rapidly picked up in the mouth of the female. Remember, it is
the male who carries the eggs.
The female would spit an egg out, and then grab it back - or, so I
thought. The male's repeated attempts to retrieve an egg during this
game of catch always appeared to go unrewarded. I watched this many
dozens of times, and I would have said that the female was so fast
that the male never caught a single egg. Well, his mouth was quicker
than my eye. After a while, it became clear that his buccal cavity
(that is, the upper throat area) was expanding, and that he had,
indeed, succeeded in grabbing an egg here and there until he was
holding virtually all of them. Eventually, both fish retired to the
cave, where a different kind of metamorphosis took place.
Let me backtrack a little, and give you some statistics on the
original environment of the adults. You already know that the tank
had a volume of two and one half gallons, and a triangular-shaped
sponge filter. This is the filter of choice for these fish because
the water remains relatively calm. It had a bare bottom, and there
were several Java Ferns (Microsorium pteropus) floating
freely. There was no heater in the tank. Even in the winter, it
would stay as warm as 84F. It received indirect lighting from the
room and a nearby window. The pH measured in at 6.8 (slightly
acidic). Both the GH (general hardness) and CH (carbonate hardness)
tested to be extremely soft, with less than one degree of hardness.
This tank was TIGHTLY COVERED. If they can fit through a
crevice, they will. Even feeding time is a "jumping hazard."
Dried foods were not readily accepted, and their regular feedings
consisted of live foods; adult brine shrimp and blackworms. More
often than not, the brine shrimp were doused in liquid vitamins.
We gave the tank a 50% water change every two weeks. The only
special treatment this tank received was the addition of black water
extract to our Bronx tap water (which is neutral and soft). Black
water extract helps to simulate the soft, acidic water in areas
where rainwater is combined with decaying plant material.
In the past, Al and I have observed the spawning behavior of the
Siamese Fighting Fish (Betta splendens), and two aspects of
the behavior of the Betta enisae
stand out in contrast. When the Siamese Fighters are spawning, there
are torn fins, missing scales, bloody lips, and a female, although
badly battered, which will predate her own eggs, eating them right
out of the bubblenest.
Betta enisae are most notable for the peaceful nature of their
relationship. They are gentle, almost tender, in their encounters.
Neither are wounded. There is, of course, no way to tell if they eat
some of the eggs during their exchanges, but we observed no
predation of the fry. A possible exception could be that they may
eat any weak or deformed offspring, as there was absolutely no
culling for us to do.
When your fish spawn three times in eight days, you suddenly find
yourself with a lot of hungry mouths to feed. Where to begin? We fed
the following foods to the fry, hoping that there was something for
every size of mouth: 1) Liquifry for egg layers, 2) newly hatched
brine shrimp and 3) microworms. Actually, the fry that have grown
the fastest are the few that remain in the tank with the parents. We
have seen them nibbling on the large blackworms that we feed to the
Cheek To Cheek
This pair of fish exhibit a behavior which can safely be described
as rare, and quite possibly borders on unique. As they co-habit
their hollow log, they spend many hours at a time in physical
contact with each other. Their bodies are touching!
This is not part of the posturing, embracing, or manipulating of
eggs that takes place during spawning. This is how they spend much,
if not most, of their time. This was probably taking place behind
and/or under the sponge filter in the other tank, but we had not
21st Century Photography
We took between 450 and 500 photographs of the events of "Second
Sunday." We used a digital camera, which captures images, not on
film, but on "SmartMedia." These are very small "disks" which
measure one and one half inches by one and three quarter inches. The
photos can be read directly by a computer where they can be sized,
cropped, e-mailed, and, yes, even printed!
The length of a battery charge on the camera would not exceed an
hour of continuous use. Our photo session lasted several hours. It
just so happened that this aquarium was within cord length of a
power strip, so we had the camera plugged in the entire time.
We used a "bipod" to stabilize the camera. This was nothing more
hi-tech than a tripod with only two of its feet standing on the
bottom ledge of the hutch, approximately one inch above the floor.
As I snapped photo after photo and filled each disk, Al "emptied" it
onto a Zip disk (another media for computer data storage), returning
the clean ones to me. We were working at the highest resolution our
camera supported. This means that we were getting the fewest number
of shots per disk, with the highest amount of detail.
Then came the "culling" process. We scanned through the photos,
deleting the ones that were not up to
Modern Aquarium standards. I was afraid there wouldn't be much
left when we got done, but after the first cut, we still had 50
photos to work with.
Tales of Transformation
If a butterfly was a mouthbrooder, it would open its mouth and a
swarm of tiny butterfly fry would come fluttering out. If a
caterpillar was a fish, it would emerge from its cocoon as a
Sometimes change is subtle and silent, and sometimes it is bold and
blaring. Sometimes we are the transformers, and sometimes we are the
transformed. Always, we must be open to the adventure of
Adult B. enisae pair. Female is on top, male is on bottom
B. enisae pair peeking out of their "cave." The male is
on the lower left,
the female on the upper right.
Look carefully and you'll see a small white spot between the two fish.
This is an egg
being tossed by the female (right) to the male (left), a process that
was repeated many times.
Male with obviously swollen buccal cavity holding eggs.
New Websters Dictionary and Thesaurus of the English Language,
Lexicon Publications, Inc., 1992
Aqualog: All Labyrinths by Frank Schafer, Verlag A. C. S., 1997
Baensch Aquarium Atlas, Volume 1
by Dr. Rüdiger Riehl and Hans A. Baensch, Tetra Press, 1991.