Saharduin

The Saharduin or Saharduins are a species of amphibian xenos that possess gills, erect posture, four webbed limbs and a long, finned tail.

Their troops, known as Piscean Warriors, are armed with wave-bladed swords and rifles similar to Imperial Bolters, and carry backpacks connected by tubes to their gills, which presumably allow them to survive out of the water.

Their domains fell before the Legion of the Space Wolves at some point during the Great Crusade. Even today the planets of Saharduin remain dark and unexplored.

The Space Marine Chapter of the White Scars is known to have fought against these dreaded aliens at some point during the 41st Millennium - Scout-Sergeant Kholka spent a whole year in the depths of the enemy territory in this engagement.