Aliens : A, B
Humanoid Federation members are blue-skinned in appearance and have bilateral antennae and characteristically white hair. Andorians are self-described as a violent and warlike species. No members of this Federation race were aboard the U.S.S. Enterprise, NCC-1701-D when Data's offspring, Lal, was "born." Lal rejected an Andorian female as one of four final choices for a racial type, instead opting to become a human female. Apparently, according to Data on stardate 43657.0, Andorians engage in group marriages of four as a rule. However, most of what is known about this race is scattered.
Water-breathing race on the planet Argo. Earthquakes forced the senior generation, who originally were air-breathers, underwater where they mutated to become water-breathers. As the centuries past, the mutations became hereditary. Other air-breathers hunted and killed the water-breathers, which is why they fear them so much. Laws forbade any Aquan from mutating back to air-breathing form. The younger generations sought the ways of the older generations and relocated to the surface when the U.S.S. Enterprise relieved the tectonic stress on Argo with their phaser banks. The younger Aquans planned to rebuild the lost cities of the old generation.
Aggressive water monster inhabiting the water world of Argo. The venom found in their teeth is an essential ingredient in reversing the water-breather transformation process.
"The Ambergris Element"
Aliens indigenous to the antimatter universe which is parallel to our own. Since time flows backwards in the antimatter universe, the Arretian aging process is reversed as well. Born elderly they regress into children as they age until finally their DNA breaks down. Arretians also favour placing numbers in their first names.
Episode Reference - "The Counter-Clock Incident"