Maybe they were CN because poison is illegal? Anyway, true neutral is much better. Where's your alignment line, anyway? Looking good otherwise.
That seems like all it should have. Here's a little seasoning:
"The cobra fish is a narrow fish shaped like a snake or eel, covered in bright silver scales. Like a snake, they strike at their prey, inflicting a weak bite with a potent venom. They often leave the water for minutes at a time, searching for land-bound prey."
That could probably be improved.
By the way, shouldn't the bite damage have a -3 Str penalty on it?
Right, but shouldn't we write it as 1d2-3 damage (or up to 1d4-3)? Isn't the damage penalty supposed to be listed?
Just drop the bit about swallowing prey whole?