A tiny goby hitchhiking on a nudibranch
The nudibranch below, Hypselodoris bullockii, more commonly called Bullock's Hyperselodoris, is a very colorful nudibranch hailing from the Tropical Western Pacific Ocean and the eastern Indian Ocean. They are found with quite a variety of colors, ranging from light pinks and oranges all the way to dark purples and blues. It is highly variable and quite beautiful.
Below is a 2:20 minute video of Bullock's Hyperselodoris, which was shot by Vimeo member liquidguru. What's interesting about this video is at about 30 seconds into the movie, the viewer receives an unexpected surprise: an unidentified hitchhiking goby.
We have heard of hitchhiking shrimp on nudibranchs, but never hitchhiking fish: