The levels, stats, and money of all the fishy guys have been adjusted to make it more of a place to go to complete the quests and get the items contained inside, rather than a good place to hunt. Now that it is an important part of the game progression, we don't want random people hanging out in there hunting for XP and cash. You will find those sea dwellers to be quite stingy with both cash and XP now compared to their difficulty in battle.
They still give out the same cool armor, though.