This is Blu, one of my Mermal characters :3

Mermal are like mermen, except for one thing. they're mammals >:3

they can breathe under water, but their blood is warm, their skin is incredibly insulated against the cold, and their fins only regrow if they're completely severed ;.;. also, their genetalia are always hidden, unless they're extremely aroused, or are getting ready to mate (with themself or others x3) they DO have external testicles (and the skin on them is just as soft as everywhere else ;3)