It was visual. The fish seemed closer to each other than was possible but there was no hint that it was an illusion. You could see into the fish while looking at their outsides. You could see what the fish sees at the same time as seeing what another sea creature nearby could see ,all overlapping yet there wasn’t any obvious glass distortions.

You could see into the fish while looking at their outsides. You could see what the fish sees at the same time as seeing what another sea creature nearby could see ,all overlapping yet there wasn’t any obvious glass distortions.