FYI, I don't remember this fish and I can't check at the moment but I believe only stuff that crafts into something has a label that says "Crafting Material" under its description. Anything else that doesn't have "Crafting Material" on it is intended to be sold to NPC, at least for now. Also they might end up being the Grand Company turn-in items but I found it better to just go after the fish after seeing it requested rather than holding on to random fish on the offchance they might be the next one for turn-ins.