I absolutely cannot find this comic anywhere. I read it maybe 5 or 10 years ago. It had amazing artwork, similar to Rick Remender. It was kinda like the series Low, but not quite.
There was a young woman protagonist, and she had to go on a deep sea voyage to find something at the bottom of the sea. Can't remember the details. But there was this Abe Sapien looking sea creature they kept in a giant glass tank. The fish people eventually started killing people. They had hallucinogenic properties and could make people see things that weren't there....and they would use this to their advantage and absolutely slaughter the humans.
There were two main story branches. One with the young woman scientist lady kinda in modern day, discovering these deep sea fishmen monsters. And then it would jump to the distant future with another young woman protagonist with her pet dolphin. Kinda post apocalyptic. God, I can't remember the name! And it's hard to seach for "comics based on deep sea" etc. Does this sound familiar to any of you?