When To Breed AxolotlsEdit
Axolotls can reach sexual maturity anywhere between 5 months and several years, depending on frequency and quality of food, and the water temperature and conditions in which the animals are kept. My personal record for a fully mature male is just under 6 months (at 25 cm or 10 inches).
Axolotls generally begin to mature once they have reached about 18 cm (7 inches) in total length. Females tend to take a little longer to mature than males (usually a difference of a month or two). The Biology Page has a great deal of information about sexing axolotls and their sexual maturity.
It is advisable that you don't attemt to breed axolotls until they reach at least 18 months of age. This gives them time to reach their full size (greater than 30 cm or 12 inches in many cases) and condition. Females should be prevented from breeding until they reach their full size.
Why not breed Females early?Edit
There is a very good reason for not breeding your female axolotl(s) too early. A female axolotl can lay in excess of 1000 eggs. Producing so many eggs is a strain on the animal's metabolism, and the body prioritises production of eggs over body growth while the animal is in conditions suitable for breeding. Since females may breed several times each year, as soon as the first batch of eggs are laid, the body attempts to produce new eggs to replace those that have been laid. Female axolotls may fall ill at this point unless due care is taken, and for a female that is still growing in length, the strain is increased. For the same reason, females that have recently bred should be kept away from males for at least a month, preferably two or three, in order for them to recover.