Prob nothing like a legit adoption thing but I'll make some here and there.
Telkies are a semi-aquatic subspecies of pony found around the coasts. They are normally no bigger than your everyday pony, however they are frightfully strong and can easily pull prey into the ocean to finish them off. These Creatures have no birth gender and can choose whether to be male, female or nothing. However there has been cases of them identifying as something else.
The diet of a telkie revolves mainly around meat, whether it be a fish or an unlucky mammal that got to close. They have also been known to eat kelp or grass if sick.
Each telkie has a fish like tail made of water, most catch fish or sea creatures within it for stored snacks or companions. Some have even been spotted with water manes as well!
Telkies also seem to have cloven hooves with webbing between the toes for better swimming, pair that with the skin "wings" that are located under each foreleg allows telkies to be fast and terrifying swimmers.