Galactic fish is a valuable catch in the Harvest Moon game. This creature can be found in the stream during rainy weather and at night. If you manage to reel in a Stardew eel, you can sell it for a handsome profit. In addition to its monetary value, it is also in demand by fishermen for its captivating charm. So, grab your angler gear and head to the streamside to try your luck at capturing this Cosmic heart fish. Happy fishing!

Eel Stardew Valley Wiki