Giant Oarfish

You catch Giant Oarfish at Desert Depths. It is a Mythic fish, so you need a rod of level 16 or higher. It is omnivorous, so any bait works. When a Mythic fish takes your bait here, it is Giant Oarfish 100% of the time, whichever bait you use.

In the Aquarium it earns 2,400 Gold an hour.