OMG this is like crazy! O_O very awesome line work, amazing shading, great darkening of lines in the proper places, it's perfect! A perfect concept of this creature. Wow! Man I wish I could put the kind of detail in my work the way you do x_x
The aboleth has always been a creepy thing. I really like the alien tentacle feel. It reminds me of something out of an H.P. Lovecraft story. The combination with the fish like form makes more sense than some of the other renditions I've seen. A nightmare abberation to meet. I would love to see it in color.
Still I think it would be nice to see some physical variants of this beast. Play around with the placement of the eyes, how many tentacles the thing has, how them emerge from the body. maybe see some different 'fish' influences, like some of the prehistoric monster fish body types and stuff.
Still, you've work to do and money to earn, so there's not much left for you to just 'muck about'.