The stuff I got came in a blue cylinder with a yellow/gold cap.
Made by Seachem, simply called Metronidazole.
I know that Metronidazole is also an active ingredient in at least one other of Seachem's medications as well.
I use it for all new acquisitions while they're in quarantine.
Mix a spoonful with a week's worth of food and feed daily, i do this for 2 weeks.
Takes care of possible internal protozoans and some bacteria.