Raining fish is not something common.
Still, people have reported such events for centuries.
Waterspouts, are essentially tornadoes over water.
They're formed when cold air moves over warm water.
They churn at speeds up to 200 miles an hour, but dissipate when rain begins to fall from their host cloud.
Depending on how fast the winds are whipping, anything that is within about one yard of the surface of the water, including sailboats or fish of different sizes, can be lifted.