Similar to what BioShock originally had conceptualized before finalizing the Splicers, BioShock 2 would have revisited the concept of a Splicer genetically mutated into an aquatic creature, known as an Aqua Splicer. Jeff Weir, animation supervisor at 2K Marine, and Colin Fix, Lead Artist in BioShock 2 and artist behind Aqua Splicer, describe the process of it's creation in Deco Devolution: The Art of BioShock 2 .
Colin Fix: "We had a monster where there were two forms of him. When you're inside Rapture, it would be more upright and have a more humanoid look to it. When it would go out in the water, what looked like it's arms when it was on land become its legs, more or less and it's fins, and that would propel it".
Jeff Weir: "We also had some idea of having leeches or parasites on these splicers, It would be visually interesting because you would be going through Rapture and come around a corner and there would be a bunch of leeches flopping around and you'd be warned that these splicers were near. It was a visual cue that shit was going to hit the fan."
Colin Fix: "That was a big thing that Jordan wanted to push for- translucency in the splicers and also bioluminescence."
Jeff Weir: "They have these little air sacks for breathing underwater."
Despite the effort in it's creation, Aqua Splicer would eventually be removed before the game's final development. The character's existence would appear in Deco Devolution, along with some additional concepts. Many initial sketches to the Aqua Splicer's pose show that Fix used two of his finished Splicer characters during it's creation: the Brute's pose for it's stature, and the Crawler for it's final design (bottom right).