Haven't read all the knowledge DC results, due to being pressed for time, but I always do like a touch of the Lovecraftian. Lovecraft's own work makes one wonder if he was an ichthyophobe, but the deep ocean is certainly a source of the unknown. I once heard it said that we know more about deep space than the deep ocean, and I can believe it.

I think too many fantasy worlds neglect the ocean and focus on the land, so I always try and make sure my settings has at least a few sapient races in the ocean.

Generally when I think of underwater monstrosities I think of The Ocean Hunter, but I do love those illustrations you linked. All aberrations coming from the deep ocean is an interesting idea, as is some real-world creatures being made into aberrations (deep-sea lie tends to look the part). I haven't read the full OP, as I say, but if aberrations come from the ocean, and life comes from the ocean... which form of life is truly "aberrant?"