Fishing slots set a rod, boat, float, or tackle box against lake or open water....

https://wiki-byte.win/index.php/Why_a_Fishing_Theme_Gives_Designers_So_Many_Ready-Made_Symbols

Fishing slots set a rod, boat, float, or tackle box against lake or open water. A still lake feels calm; the wide sea feels brisk. The fisherman may be a sly old hand or a keen new face. See which mood and style fit you, and what each game gets right, too