Gold Frog

Gold critters replace their ordinary version on a rare roll, and a frog is small and quick even when it is shiny. A Lifeform Analyzer is the only dependable way to know one exists nearby, since it names rare spawns on the info bar the moment they appear. Without it you are hoping to catch a yellow flicker at the edge of the screen before it hops off it.

Selling is the obvious answer and the payout is absurd for a critter. Caging it keeps the same value if you change your mind later, so there is no rush. The third option is Golden Delight, which turns it into a food buff, and that is the one worth considering if you already have gold coming in and want the strongest well fed effect for a boss night.