According to the game scenario, the Inter-Dimensional Espionage sends operatives throughout the dimensions to fight evil. This is done by possessing someone's body and controlling his actions.
The player is Agent 10 who enjoys his leave of absence in the body of a goldfish. He learns that an inter-dimensional terrorist group named the Seven Deadly Fins have stolen a focus wheel. In the first part of the game, the player can visit three dimensions (a forest with a smithy, a hippie van near an abbey and a recording studio).
Once the three parts of the wheel are gathered, he learns that the Fins are threatening to take over the water-world of Hydropolis by evaporating the ocean of that planet. The player must warp to Hydropolis to foil the Seven Deadly Fins. The player possesses Dr. Roach, who is in charge of the Project that will transfer water from another dimension to keep Hydropolis alive.
The game is a standard text adventure with static graphics in some versions.
The game was re-released as part of the Magnetic Scrolls Collection, featuring a Graphical user interface with an auto-map system, inventory, and pop-down menus.
The game was voted Best 16-bit Adventure Game of the Year at the Golden Joystick Awards. Charles Ardai of Computer Gaming World wrote in 1992 when reviewing Magnetic Scrolls Collection that Fish! was "just a shade too crazy. Unpredictable is good; incomprehensible is not", but "if nothing else, this makes the game original" and had "the most clever gags of the three games".
- Meier, Stefan. "Magnetic Scrolls Fact Sheet". Retrieved 17 June 2015.
- Andrew Rollings, Ernest Adams Andrew Rollings and Ernest Adams on Game Design 2003 p155 "... writing correspondingly improved with the increasing capabilities of the target machines. Games such as The Hitchhiker's Guide to the Galaxy from Infocom (publishers of the original Zork series of games) and Fish! from Magnetic Scrolls are ..."
- Nick Montfort Twisty Little Passages: An Approach to Interactive Fiction 2005 -p188 "The capable parser did allow Magnetic Scrolls to surpass some of its competitors who had started out producing works ... A different conflation of influences could be seen in Fish!, a work by multiple authors that has been called “something like ...""
- "Golden Joystick Awards 1989". Computer and Video Games (Future Publishing) (92): 62–63. June 1989.
- Ardai, Charles (November 1992). "Virgin Software's Magnetic Scrolls Collection". Computer Gaming World. pp. 64–64. Retrieved 4 July 2014.