I have bred axolotls by the bucket load, cool creatures
BUT it is not stressful for them to metamorphosis some just choose to do it and can even start to change but dont complete the morph and just change back.
Usually they morph when the salts in the water get high this causes the axolotl's thyroid to produce higher levels of thyroxine which will induce metamorphosis. i kept mine in a bath outside and when i went away some times the water would evaporate to about 6 inches and id usualy come home to a salamander
This can also be achieved by adding the CORRECT amount iodine to the water, Not medical iodine BUT Iodine used in SW aquariums. Tthere is no real need to do this though spawning them as salamanders is alot harder and they produce less eggs.
