There are several "moving objects" that can be added to the tanks which the fish will react to, such as a cat paw, fibcrab, and a small plastic scuba diver.

El-Fish was created by Vladimir Pokhilko, Ph.D. and Alexey Pajitnov (the creator of Tetris), who had backgrounds in mathematics, computer science, and psychology.

They were attempting to create software for INTEC (a company that they started) that would be made for "people's souls".

The reviewer, an aquarium owner, criticized the "software toy" on its "inability to sustain the player's interest.

Once the aquarium has been created and viewed, there just isn't much else happening", with no simulation of an ecosystem needing ongoing maintenance as he had hoped.