Well...
Because if there isn't an intervention
Then by god, 'Mina and Nausithoe will
End up cannonized.
UDB
Melu-Kobold
Koi Melusi
While there are many who claim that the Rey-kobold are the first clearly aquatic or otherwise liquid based race to become interstellar with any relative frequency, most of their race remains planet bound, for obvious reasons. As such, the first race to become majoritively interstellar, is the Koi Melusi, officially called the Melu-Kobold, and more often referred to as the Siren or Mermaid.
Melu-kobold are hairless, and appear roughly standard in many ways. Their faces are clearly standard, as are their abdomens- upper and lower- and arms. Indeed, even their reproductive organs are compatible with standard races, unlike the Rey-kobold, though males' are internal until needed. However, from the pelvis, one does not find a few long bones supporting legs, as one does in standard humanoids. Instead, there are two appendages identified as tails, ending in large, translucent, homoceral fins. These tails tend to be between two and three times the length of the Melu-kobold's torso, are rarely wider than a common standard leg, and are full prehensile.
Aside from these tails, Melu-kobold have anterior fins on their forarms, which can be expanded and contracted freely are rarely measure wider than two arm widths, and dorsal fins located below the shoulder and extended anywhere from twelve to thirty inches down the back and are very rarely larger than a foot wide. Finally, they have a variety of differently shaped fins upon their heads, which can give the general appearance of hair on some.
Aesthetically, Melu-kobold colors range widely, and though it is common for the tails to be the same shade as the rest of the body, this is not always the case. Indeed, the most famous of the Melu-kobold, Alysee Sire, is noted for her unnervingly Rani-like torso of cream white with red spots, and her black with red-spots tails, as well as her abnormally large dorsal fins, giving the appearance of wings.
Melu-kobold are covered in a standard skin, and have no scales, leading to a theory that they evolved from a dead eel-like ancestor, rather than the two tailed fish that fill the waters of their home planet. This is supported by their copper based blood, which is shared only by a handful of native invertebrates.
Melu-kobold are a magic driven race of unusually fast advancement. There appears to be a very strong urge among them to explore and expand their territory, and given a few hundred generations, they will likely become a powerful Empire race.
Due to their obvious lack of mobility in air, they have created a particularly powerful brand of liquid element magic. Though early life testing has poven that they are capable of other magical abilities, these other avenues are nearly never explored. Instead, their culture focuses on training its young to move in standard atmospheres by creating a type of bubble around themselves, constantly reoxygenated by the surrounding air, through which they can propel themselves. Technically, the actions of swimming are not required, as the bubble is what moves, not the body. However, it is considered a capital form of sloth to not swim in one's sphere.
Particularly advanced Melu-kobold magicians are able to reduce the sphere to little more than a skin of water around themselves, mesauring only a handful of molecules thick, and giving the impression that they are simply swimming in the air.