That Reptile Blog – Reptile, Amphibian and Exotic Pet Care and Information

Lengthening days and warmer temperatures are beginning to register on amphibian pets nationwide, stirring long-dormant breeding urges.  Last week I was please to find that a 2 year old female axolotl (Ambystoma mexicanum) which I paired with an older male had produced eggs for the first time.  A week or so earlier a reader informed me of another spontaneous axolotl breeding.

Mexican axolotls are an ideal choice for the prospective amphibian breeder, and are becoming ever more popular each year.  With spring upon us, I thought I might pass along some photos of my pair and their eggs, along with a few tips.

The Aquarium and Filter

The eggs pictured here are set up in a PLA House Plastic Cage equipped with a Small World Filter.  PLA House Cages are available in 6 sizes, and their light weight allows for easy water changes.  I have found them indispensible in my collection, and always have a number on hand.

The Small World Filter is ideal for use with amphibian larvae, as the water return is directed upwards and so does hamper weak swimmers.  Sponge filters work equally well.  I use an air pump that provides just enough aeration to keep the eggs slightly in motion.

Providing Cover
Axolotl eggs are typically attached to plants or other structures, as seen in the accompanying photo.  Once they begin to hatch, I’ll add additional plants, nearly filling the tank so as to separate the larvae a bit and reduce cannibalism.  Plastic plants set in bases are very useful, as they provide shelter throughout the water column. The Cypress Mat  provides excellent cover on the bottom of the aquarium, where the larvae will be spending most of their time.

Feeding Axolotl Larvae
Finely chopped live blackworms form the basis of my diet for newly hatched larvae…a worm feeder lessens the likelihood of the worms clumping together (larvae often choke while trying to swallow large balls of worms).  A brine shrimp hatchery is also useful, and larvae can sometimes be induced to accept freeze dried daphnia and other invertebrates as well.

Further Reading
Pleased see my article Breeding Mexican Axolotls  for additional breeding recommendations.

Please see The Natural History of Axolotls and The Captive Care of Axolotls for further information on this fascinating captives.  Today I’ll finish up with a note on reproduction.

Inducing Reproduction

Adult axolotls are sexually dimorphic, with females being of a heavier build and having shorter and broader heads than males.  The cloaca of the male is noticeably swollen during the breeding season, and gravid females become very plump.

The natural change in day length and room temperature in temperate regions is often enough to stimulate reproduction.  Animals under my care in NY respond to natural variations in room temperature (they are housed in a cool basement) and possibly day-length (light enters through a ground level window).  Females generally lay from January through March, sometimes into April, at water temperatures of 55-60 F.

A sudden increase of water volume and a drop in water temperature seems to stimulate breeding even outside of the normal breeding season. Be careful, however, that females actually lay their eggs when artificial methods such as this are utilized. Retained eggs are a great concern among many captive amphibians, although I have not run into such with axolotls.

The Eggs

Please see the Natural History of Axolotls for details on courtship and mating.  Females have been observed to pick up several spermatophores during the night, although it is not clear all are from one or several males.  Eggs are attached to water plants or any other substrate within the tank. Plastic plants make ideal deposition sites (from a pet-keepers point of view!) as they are easily removed from the aquarium.

Axolotls are ravenous consumers of their own eggs, and few will survive if the adults are left in the same tank. At temperatures of 55 to 60°F, the eggs will hatch within two to three weeks. I generally provide them with mild aeration, just enough to keep the eggs slightly moving. Eggs deposited on plants and on floating objects seem to have a higher hatch rate than do those laid along the bottom of the aquarium, so be sure to provide suitable sites for your females.

Caring for Axolotl Larvae

The larvae lie motionless for a day or so after hatching, after which they become veritable eating machines.  They are best raised in a bare-bottomed plastic or glass aquarium.  Mild aeration via the return from a corner or sponge filter should be provided.  The young require daily feedings and very frequent water changes – after having raised 160 to adulthood at one point, I can vouch for this as being a labor-intensive but ultimately rewarding task.

I’ve found light plastic terrariums or sweater boxes that can be easily dumped and filled to be the method of choice when rearing large numbers of salamanders.  I’ve also used plastic wading pools, but unless you can arrange a way to drain and re-fill easily, these can be a bit un-wieldy to work with.  The extra room they provide does, however cut down on cannibalism.  Please see Captive Care of the Mexican Axolotl (Physical Environment, Feeding) for tips on setting up enclosures and feeding axolotl larvae.

The IUCN’s recommended conservation strategy for this species, as well as historical and natural history information, is posted at:

http://www.iucnredlist.org/details/1095