Beginning as an egg, tomato clownfish will take about one week to hatch and become larvae. After hatching, larvae will drift for about 16 days in plankton-rich waters. At the end of this drifting journey, the larvae will look for anemones of their own to inhabit. Their development from there depends upon social roles. A juvenile will only develop into a sexually mature male if this role in the anemone is not already filled. When the female of the anemone is absent, the largest mature male will then change into the sexually mature female.
Damselfishes that live in anemones have biological attributes that help them to live in this unique environment. As they mature, they gain a special mucus coat that has specific chemicals that counter the anemone's sting. These fishes are also known to have a special swimming pattern that helps them to survive in the anemone.
According to Wickler (1963), Amphiprion frenatus, like other anemonefishes, is not immune to the anemone, but instead stimulates the nematocysts (stinging cells) to fire. If these fish choose to live outside of an anemone, they usually take up residence in coral branches.
It is possible to make a general guess at the age of tomato clownfish by the stripes on their bodies. When young, these fish will have more white stripes on their hind regions. However, not all individuals lose the juvenile pattern as they mature.