Right now for anti-fungal i have Mardel Maroxy which is liquid , gram positive too, because I had to medicate my brackish puffers and it covered salt and freshwater. I do have Mardel Maracyn-Two tablets for anti-bacteria is broad spectrum. I also have, now that im looking API MelaFix which is nice for open wounds on fish I use it a lot after breeding's. The internal parasite pellet food i have is by Jungle.
I think for a supply kit a broad spectrum needs should be included.
I have heard fish are usually infected most of the time with gram negative bacteria but I'm not sure about it.