A reference of over-the-counter freshwater aquarium medications.
I am not a pharmacist nor a vet. I wrote this for my own reference. Verify usage and dosage yourself. Using these improperly can kill fish, kill plants, disrupt nitrogen cycles, or leave permanent stains. Follow at your own risk.
Antibiotics
Kanamycin sulfate
Type: Antibiotic pharmaceutical
Use: Fin rot, dropsy, pop-eye, columnaris
Contained In: Seachem Kanaplex
Erythromycin
Type: Antibiotic pharmaceutical
Use: Fin rot, pop-eye, columnaris
Contained In: Fritz Maracyn, API E.M. Erythromycin
Use: Flukes, general internal parasites, especially the Tapeworm
Contained In: Hikari PraziPro, Fritz PraziCleanse, Fritz Paracleanse, API General Cure
Metronidazole
Type: Antiparasitic pharmaceutical
Use: hole-in-head, general internal parasites
Contained In: Seachem MetroPlex, Fritz MetroClenaseFritz Paracleanse, API General Cure
Metronidazole may be a human carcinogen
Some aldehyde (formaldehyde (see note on carcinogenity) or glutaraldehyde) withMalachite green
Type: Chemical compound
Use: Ich, velvet, flukes
Brands: Hikari Ich-X, API Super Ick, Seachem ParaGuard
Formaldehyde is known a human carcinogen, and malachite green is considered to potentially be one too. Conversely, glutaraldehydes are not thought to be carcinogenic.
For this reason alone I avoid using formaldehydes because I’m sticking my arms in the tank water all the time. Since these are used for parasitic treatments, I recommend instead one of the glutaraldehyde-based liquids, one of the pharmaceuticals, or copper as a safer alternative.
Quinacrine dihydrochloride
Type: Antiparasitic pharmaceutical
Use: hole-in-head
Contained In: Seachem Polyguard
Levamisole hydrochloride
Type: Antiparasitic pharmaceutical
Use: general internal parasites, especially the Callamanus worm
Between brands, copper treatments are chemically different.
In forms like Copper Power or Coppersafe, the copper is present in a “chelated” form, which locks the copper inside other organic molecules, making it less “aggressive”. These types of copper are ideal as a first, less aggressive treatment option if the disease is caught early.
In Cupramine, the copper form is bound instead to an ammonia-like compound to prevent it from being toxic. Cupramine therefore cannot be safely mixed in tanks which have used common water/ammonia conditioners like Seachem Prime because the conditioner can instantly break the copper away from its amine-bond, making it instantly more toxic to all fish. For that reason, amine-bound coppers like Cupramine are probably better as second options, i.e. in tightly controlled quarantine tanks or in cases where the disease is already very progressed.
Copper in miniscule amounts will eradicate invertebrates like snails and shrimp.
Non-drug / natural ingredient
Salt (sodium chloride)
Type: Chemical compound
Use: Osmogregulation (fish breathing), inhibiting growth of bacteria/fungus/parasites
Salts do not evaporate. You need to be mindful of how much salt you add over time. To remove salt, you must do water-removals.
Epsom salt (magnesium sulfate)
Type: Chemical compound
Use: Constipation
Tree extract oils
Type: Natural extract
Use: Dubious anti-microbial properties
These are often marketed at “fixes” and “remedies”. In my experience these do not do anything. You are better off finding a real drug.
Contained In: API Melafix, API Pimafix, API Bettafix, Imagitarium Bacterial Remedy