I believe I discussed a bit of this in the "Felaryan Locations" thread, but here is where I go in-depth.
The Botortu appeared to be lifeforms similar to those spoken of in pseudo-Spanish lore. To be specific, the lore mentioned creatures that could change into humans and into porpoises on a full moon, and were able to create others like them.
Now, the ones in Felarya were distinctively different. They had an innate ability to morph at will into three forms- from a blue human to a mermaid or to a full blown porpoise. Each form had their own advantages.
The humanoid state allowed them to walk among the humans and other creatures on land. They require little to no water while in this form. Oddly enough, when they're in the forest, they are avoided by most predators. That may be because they bear a striking resemblance to the voracious Anko the mermaid. They feel that Anko watches over them, getting revenge against those that eat her friends. Most of the Botortu don't know Anko that well, and are baffled by how this rumor started. Since it keeps them from being eaten, they go along with it. This also works against them in a way, as the predators that hate Anko and the mermaids are more than happy to eat them by the dozens. It's a cost they're willing to make to survive, though.
Now, the mermaid form is often popular among their people. It allows them the advantages of human appendages while giving them a good grasp of mobility in the water. In their homes, this is the form they take the most, as it allows them to function as a human society underwater.
Their last transformation, that of a porpoise, is very unique. In this form, they can talk to all aquatic life much easier. They can reach speeds of up to several knots, even in bad currents. This form is also their predator state. They hunt most efficiently as porpoises.
Their diet consists of small fish, seaweed, and other types of seafood. However, in their human forms, they are more than happy to eat regular foods.
As for their relationships with predators, they are often left alone. Unfortunately, some species do not know the mermaids well and will eat them on the spot. They are also devoured by the mermaids' enemies. It's a sad thing to see. If the predators are friends with the mermaids, then they will not eat them. In fact, just about all aquatic life is friendly with them, so they don't have much to fear.
They are fascinated by humans and their strange contraptions. Every so often they'll visit a human encampment and mingle. They've heard the stories of humans and their pollution of the Earth, but still they like them, and so long as they don't pollute their ocean, they'll remain friendly.
The majority of their race lives under the ocean waves, in a great city called "Tortantia". The reason for this name is because it is literally built on the shell of a huge tortoise, over 9 football fields in area. They care for the tortoise and keep it happy, and in return the gentle giant protects their city from large invaders. It is a snapping tortoise after all, and such symbiosis is vital for life.
Now, according to their legend, it says they can turn other lifeforms into Botortu. This is partially true. You see, the power to change others is an innate ability that all powerful Botortu used to have. Sadly, the skill has been lost over the generations, and only a few still have this ability today.
That's all I can say for this race. Do you think it is good?