Any idea what this fish is?
Your fish in question is a zebra danio GloFish; they're genetically engineered to have flourescent coloration. The giveaways for me were the shape of the body (minnow shaped, with zebrafish belonging to the minnow family), its size (small), and the striped pattern running along the body, parallel to the lateral line. Since the fish in your picture is in motion, it's a bit difficult to see, but it's definitely there (can be seen closer to the head).



And here's another image, where the coloration is closer to what you have. (IMO, the previous image has a strong contrast, especially with the black background)



This zebrafish is suffering from a bent spine, which accounts for the misshapen body. (source)





Also, it seems that the fish in the background is a black-skirt tetra.