Merfolk

There are many merfolk tribes located specifically on the planet of Aquox, the "World of Oceans."  Mermaids are the counterparts of mermen, and depending on the tribe the groups can either be incredibly friendly (going so far as to willingly interbreed and socialize with other humanoids) or incredibly hostile, going as far as to kill and eat sailors and explorers.   Merfolk also have a few issues that make them essentially symbiotic with other humanoids, namely in that all male merfolk (mermen) are actually completely sterile. Because of this in recent years their population has been decreasing dramatically. To combat this, interracial marriage and kinship has been encouraged in many tribes - although this can take a rather insidious twist in the more violent of the groups.   Generally, merfolk specialize in healing and water magics. Like other humanoids they are capable of learning other magics, but they do not synergize with them very well.   Merfolk society is just coming into their own industrial age, mostly using turbines to catch ocean currents to power their forges. Many a weapon has been forged by the merfolk, although the majority of these function best underwater and use various water magics to make them as powerful as possible.