I've found the fish for Red Summer Pareo (and most likely the maro too). Screenshot proof below. No, it is not from Shark Tuna.

I've blacked out the info since I will be first providing it to Reese's fish desynth collab google doc here to help promote it: https://docs.google.com/spreadsheets...#gid=491247152

It would be great if more people help out! They update on a daily basis so expect the information to be up within a day (if no one else finds and reports it by then). (: