Distant Yap. Take a plane: Norfolk-Houston-Honolulu-Guam-Yap. Takes about 24 hours. Find the mandarin fish. Be where they mate at dusk (it's dark underwater). Capture the mating sequence when the male and female come up out of the coral tangle for about the time it takes to say "one-thousand-one one-thousand-two one-thousand-three." The same pair might do it twice or the male may go find another female. You have 15 minutes and it's over.

I was sick (from some airplane germ, I think), but went out three nights in a row to capture the mating in the shallow water off a mangrove island in Yap. It happens about 7:15PM. This is a male just before mating. I missed the big moment.