Here is a clip of Salt Creek Pupfish swimming around and mating in Death Valley, California. Video taken be Casey Dunn, and released under a Creative Commons Attribution-Noncommercial-Share Alike license. Visit CreatureCast.org for stories, videos, photos, drawings, and animations about the unexpected world of animals.
Distal parts of the intromittent organ of Phalloptychus januarius. A, the organ as it is normally found; b, unfolded: (a, third anal ray; b, fourth anal ray; c, fifth anal ray); c, third analy ray, 1 view. d, fifth anal ray, enlarged.
This female killifish was for sale at an aquarium shop. Owners don't know the exact species because the animal was donated to the shop by a hobbyist. I cannot find in the whole Internet any Aplocheilus with a blackish longitudinal band in the flank...