I believe these are sardines. This was in a big circular room with a cylindrical aquarium above our heads, where the fish swam in circles. I think each one of these fish is about 8 inches long. Note that this was shot at 1/40th of a second at ISO 3200. I should have bumped the ISO up to 6400. It's still good but a faster shutter speed would have been better. I don't think I could have done this with any other camera, though - maybe the Nikon D800.