Been fishing for a Pufferfish (or a Clownfish, there's a recipe using Botania Mana to convert Clown into Puffer) for a half hour, I've gotten 25 Cod in a row. Not sure why I need the Salmon tho... very first cast I got a Salmon, then the next 25 have all been Cod.
Need Pufferfish so I can make an Underwater Breathing potion, which is how I'm gonna try to get my Mariculture Pearl to progress that quest...
Well any 2 of the vanilla fish will do if you have the alchemy catalyst. You can interchange between all of them by throwing a fish into the mana pool above one, it's just a loop, keep tossing until you have the ones you need. Ring of Chordata gives you unlimited underwater breathing for a salmon, a pufferfish, 4 manasteel, and a rune of water. As long as you have an item that stores mana in your inventory it works, and you really need just a tiny amount of mana. It also gives extremely fast underwater movement and night vision as long as you're underwater. It's really very preferable to any of the early mariculture options (because power) and potions (because they run out of time).