Breeding the Axolotl
Ambystoma mexicanum
by Andrew and Julie Boyd
First published in Tank Talk, Canberra and District Aquarium Society, Australia
Aquarticles
Keeping the Adults properly:
Before you can hope to breed your Axies you will need to know how to keep them alive. This
is not as easy as it sounds. They need adequate space (our breeders, four in number, live
in a three foot by two foot by one foot deep tank), decent food (mealworms are good), good
quality water, and some cover to hide in so that they feel secure, such as hollow
driftwood or rocks without sharp edges. The water must not be too hot or too cold (fifteen
to twenty degrees Celsius is ideal).
Preparation for breeding:
If you are not keeping the adults on live food, it might not be a bad idea to hunt up some
mealworms, earthworms, water boatmen, or feeder goldfish or guppies to plump up the
females (watch feeder fish to ensure they don't snack on the Axies' feathery external
gills). Do this in July/August (winter) in preparation for the breeding season, which runs
roughly August to February (summer) in our cold corner of Australia, although we have had
them spawn in July in years past. When they are ready to spawn the females will fill up
with eggs, while the males (the ones with the longer, narrower heads) seem to swell around
the vent.
The Spawning:
When the pair are properly conditioned spawning should follow as a matter of course.
Sometimes, however, they will need a nudge along. A good water change will often do the
trick, but if a change of more than 30 % is contemplated then please use aged water. We
have never had any trouble getting ours to spawn, even when on a sole diet of trout
pellets (they must have been really keen!).
After waltzing or dancing around the female, the male deposits spermatophores (sperm
packets) on rocks or driftwood. The female then picks these up, and soon begins to look
for a place to lay her eggs. Bushy plants such as Foxtail or Java Moss are preferred (the
latter for a preference, it seems to do better in lower water temperatures and light), but
any available surface can be used. Tank walls, gravel, filter risers, rocks, all are
strewn with the eggs. The eggs swell up overnight, roughly doubling in size. Usually the
first indication you will have that they have even thought of spawning will be to come out
in the morning and find the whole tank littered with lines of eggs! When they have
finished swelling (to about 8-10 mm) they can be removed to the hatching tank. Don't worry
if you have to wait a couple of days to set up your spare tank, the parents may eat an egg
or two accidentally but won't actively hunt the youngsters until after they are hatched.
Hatching takes as little as a week, or as long as a month, depending on water temperature.
Adding Methylene Blue to the hatching tank seems to accomplish nothing. Simply place
the eggs in their own tank with gentle filtration and pick out the rotten ones as they
appear. Dead in shell/infertile spawn seem to go opaque fairly quickly, and should be
removed as soon as possible. Axolotl eggs are clear, so It is possible to observe the
embryos developing. It is interesting to see the single cell divide by meiosis into many
cells over the course of days, and finally become recognisable as a growing larva. When
they get close to hatching they start to thrash about, eventually tearing the outer
membrane of the egg.
The Youngsters:
Axolotl larvae seem to need food within a day of hatching. We have tried all sorts of
first foods over the years and have yet to come up with a better one than Cyclops,
courtesy of our local farm dam.
We have tried shredded beef heart (turns the water foul), powdered trout pellet (ditto
the foul water), brine shrimp nauplii (die in the cooler water too fast, and always seem
to be hunting the light at the top of the tank, which places them out of reach of the
lazier, younger larvae) and frozen foods of different sorts that never seemed to work that
well. We have never killed off a spawning with disease brought in 'from the wild', but
suppose that there is some risk of this. It is probably likely that we never will bring a
disease home that will affect the Axies, owing to a decrease in wild amphibians, but the
risk remains. Maybe if they were cultured in a backyard pond...
For older larvae blackworms are good, provided your tank is free from any substrate
(gravel), and will take them right through to three months of age, when they can go onto
mealworms. Blackworms are a close relative of the Tubificid (Tubifex) worms, but are much
cleaner in their habits and correspondingly easier to store. At three to four months, if
you have done your job well, they are ready to go off to their new homes. We cannot
recommend placing a juvenile with an adult of more than a third greater body length,
because all you have then is an expensive breakfast for the older Axolotls.
The other requirement when raising Axolotl larvae is space. They go through a highly
cannibalistic phase, between six weeks and three months. They need to be sorted according
to size. It is not too ridiculous to allow a square foot of tank bottom (i.e. surface
area) each. otherwise you will end up with a whole lot of legless Axies (which opens them
to fungal infection) because they will snap at anything that moves, including their
siblings. This is not a bad thing in and of itself (although hard on the larvae
concerned), but it can be a real job convincing a prospective buyer that the missing limbs
will grow back.
If you can't get hold of blackworms, the youngsters can be raised entirely on daphnia
to the three-month stage, but you must be prepared to take a couple of trips a week to the
dam or sewerage works. The same goes for water boatmen, or backswimmers as they are also
known, which are relished by all ages, right up to and including adult Axies. Bloodworms
are good, but hard to find in sufficient numbers to feed a hundred hungry mouths. Mosquito
larvae tend to move too fast, thus filling the fishroom (or family home) with buzzing
mozzies. If you were really keen you could put earthworms through the kitchen blender, but
like the aforementioned beefheart this would go off quickly. We did raise eighty odd
youngsters a couple of years ago entirely on trout pellets, but it meant an hour a day,
every day, siphoning off the half rotten uneaten stuff, and believe me, the novelty soon
wore off.
It may sometimes happen that some of your youngsters will lose their frilly external
gills, their tails will become narrower, their eyes looking like bugging right out of
their heads. These are metamorphosing into the 'adult' salamander form, in fact are
properly called Mexican Salamanders. This happened to us for the first time this year, and
was quite a surprise. We were raising this year's larvae in fiberglass vats outside in our
back yard. A lot of leaves fell from a neighbour's trees into one particular vat, turning
it very acid. When this was noticed the larvae were already on their way to adulthood.
They need to breath atmospheric oxygen to survive, so are in different accommodations with
shallower water and rocks to crawl on to. I am building them a palludarium (another
article) so that they can enjoy the best of both worlds, wet and dry. There are not a lot
of references to the metamorphosed form in the literature so we are experimenting to find
the best possible housing for them. They continue to feed in the water so larger aquatic
insects and mealworms are sustaining them at the moment.
The raising of Axolotls is not an easy task. They need about the same level of care as
large tropical fish fry. But don't let that discourage you. If you have access to live
food, have sufficient tank space, and apply yourself, you can breed and raise Axolotls.
See also: The Axolotl is Not a Fish, by David Rentz
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