Aqua Zebesians (aka Mermen Pirates) are a mutant offshoot of the Zebesians that appear in Metroid Fusion. They are created from Zebesians that have been infected with X Parasites containing Skultera DNA, giving the Zebesian the ability to swim, as well as a pair of fins and a mermaid-like tail.
Aqua Zebesians are highly manoeuvrable in the water but cannot function out of water. They also do not possess the same strength as their land-dwelling cousins, but are quick opponents and deliver deadly strikes from a distance. They are armed with galvanic blasters, though they will also charge Samus Aran if she gets too close.