Regeneration - restoration of damaged tissues and organs by the organism. To a greater extent, regeneration is inherent in invertebrates; in fish it is manifested in the restoration of gill lobes, damaged fins, scales. The process of regeneration is significantly affected by environmental conditions, availability of adequate nutrition, physiological status, age. In young fish tissue regeneration is faster than in older fish.

A special feature of the axolotl is its ability to heal: axolotls do not heal by scarring and are capable of regenerating entire lost appendages within a few months, and in some cases more vital structures such as the tail, limbs, central nervous system and eye and heart tissue. They can even regenerate less vital parts of their brain.