This is an aquatic species I've created sometime ago called Lumi. They may be aquatic but they aren't 100% as they don't have any gills, but they can stay underwater for a loooong time though and they excel at swimming.
A special trait they possess is that they have spots on their bodies that glow when they're experiencing positive emotions like happiness, love or excitement. Bioluminiscence in fact!! (That's why they're named Lumi, after all).
Most of the species live in settlements on islands or near the shores. Their whole species consists of females, but they can reproduce without any problem as they don't need any males. They just do it with each other!!