Kuo-toa, another of these elusive non-SRD monsters. They're 2 HD monstrous humanoids, which is pretty good. Their strength, constitution, intelligence, and wisdom are all above average, their charisma a bit below. They also get Alertness as a bonus feat.
Kuo-toa have a variety of special attacks, most of them incomprehensible. Lightning Bolt is both poorly-written and horrible, Pincer Staff either simply describes an exotic weapon or grants certain characters a permanent weapon that gets replaced if it leaves their possession, and Adhesive is only usable for characters with subpar fighting styles and some money to spend.
Slippery is a bit better: webs are common low-level obstacles or attacks, and Keen Sight is perhaps one of the only ways to nonmagically spot ethereal stuff. Light Blindness is annoying, though.
What class should a kuo-toa take, I wonder? The developers seem to really want them to become clerics, but with two RHD that's less than optimal. As melee characters they are reasonable, but additional LA don't seem necessary to balance them out. +0 LA.