I've seen a couple posts of people inquiring as to where they can get medaka, so I thought it would be good to have this thread. There's also a good upside of seeing where others source theirs -- going to a different seller means you might be able to find different varieties.

Personally, I've gotten mine from Aquatic Arts -- they currently have blue miyuki and blue sparkle, and have carried other [comparatively] rare varieties like the red capped ones in the past. I grabbed some youkihi when they had them.

I've also seen a bunch of really cool varieties listed on Aquabid in the Killifish section that I've never seen before in the states: black and silver lamé, yamablood, white lamé.

Unfortunately where I live [D.C. area] none of the physical fish stores near me seem to have them in person.