Got a few questions about this so I guess I should make something like it xD ( i forgot the blush in this xD so ignore that)Information
All finnedyrs are born as eggs in water, like frog eggs attatched to a surface.
When they hatch they are just like tadpoles, they can only survive in water and they are born with a huge fin to help them swim around.
At 1 week old they can start crawling out of water for some periods of time, during this period they start growing their real fin design.
They loose their tail as the new fin starts growing bigger. This is their most vounrable state as they cant swim as good until their fin is fully developed.
As young adults/adults they have their original findesign.
Old finnedyrs just look old D8< and droopy xD draw them how you want haha
They have all their markings and colors from birth.