The Virtual Fish Tank is an interactive, educational museum exhibit that was originally displayed at the Boston Computer Museum in 1998 and later moved to the Boston Museum of Science. As their website reports, this exhibit represents a shift in the presentation of scientific knowledge from “merely” observational to “interactive” scientific (and underwater) education.
In both the exhibit and the website later based on it, users build virtual fish by adjusting a variety of parameters (e.g. how much it likes bubbles, how hungry it is) and then let the fish loose in an aquarium simulation.
The focus is not so much on immersion (for example, as in Sharkbait), but on the interaction and agency afforded the user. This interaction is seen as the best way to involve and educate them with ocean animals and ecologies.