This signs was located in a shopping mall in Espoo, Finland. It shows a simplistic fish icon underneath a wave-like squiggly line. Its purpose was to index the location of some fish tanks set up as decoration.
The reason it caught my attention was that typically in shopping malls a fish-sign indexes where to go an find fish products. Not live fish! And thus the addition of the wave, signaling that this is about a fish underwater, its natural environment.