its one of those floating bog islands you see around swamps all the time, he just found an open pocket and there happened to be a fish feeding there
Never heard of a floating bog island. Sounds magical. Lucky catch for sure.
from wikipedia
A floating island is a mass of floating aquatic plants, mud, and peat ranging in thickness from a few inches to several feet. Floating islands are a common natural phenomenon that are found in many parts of the world. They exist less commonly as a man-made phenomenon. Floating islands are generally found on marshlands, lakes, and similar wetland locations, and can be many hectares in size.