I am sorry to say, Uatu, that a Sea Horse will not be included in the database. They're not in the monster books.
Now, Giant Sea Horse, it's in there.
What would the Sea Horse attack be? "You are swarmed by a school of cute little creatures that flap their fins at you and then flee." Special attack is "Distract by Cuteness".
Just out of curiosity I did a quick search on Aboleths, and didn't find anything per the 1e version in the first 20 results, but lots of references to the Pathfinder, d20 and D&D 3.5+ versions, where it is quite a bit bigger (almost twice the size), slimmer, faster and a "master of mind magic".
To me, that 1e pic in all of it's line-drawing glory, looks like a cross between a mollusk, catfish and bathosphere.
I always imagined that if I used one as a DM, I would have a gnome pilot inside.