Seems they've figured out how to wiggle themselves forward using their tails, then land in a way that creates a suction between their belly and the rocks. Clever.
I think I've seen similar videos of sculpins doing this - who have a suctiony fused set of bottom fins. If sculpins do it, probably some kind of Goby also does it (the two families are very similar in many ways).
And yes - as people point out, sea lampreys can do this with their sucky mouths. With with the variety of small fish with sucky mouths, probably there's even more who have learned this trick.
https://www.researchgate.net/publication/394405635_Bumblebee...