I've never had to dose for a bacterial infection before but I'm pretty sure I have to now. I have a fully stocked (a bit overstocked actually) 56 gallon tank that has been running for over a year now and I'm terrified of killing all of the beneficial bacteria.
If I keep the filter media in a bucket of tank water and put fish food in to create ammonia, will that keep the bacteria alive? I have no idea what to do.
Background info if you feel like reading.
Ammonia/nitrite 0. Nitrate 20. Ph 7.6. Peaceful community tank with a pearl gourami (my favorite), a few livebearers left, assorted small schooling fish, kuhlis, and 3 rams.
Changes to tank that all happened 14-20 days ago: Started New Life Spectrum anti-parasite food for white stringy poop (can't tell if it's gotten better). Replaced one of my two Marineland Penguin 200 filters with a Fluval Aquaclear 70. Got two new rams from a pet store I rarely go to and did not quarantine. This is the culprit, I suspect.
I've lost almost a third of my stock, not including the rams, with little to no symptoms beforehand, sometimes labored breathing the day before death. I wake up in the morning or come home from work and find dead fish, even hardy ones like the danios I've had since the tank started. I've been doing multiple PWC
a week since it started. Today, though, finally a symptom, two tetras with what looks like fin rot. One of them has white filmy stuff in a half-inch circle around the base of his fin, too, and some redness on the same fin. Signs are pointing an internal bacteria possibly, as well as an external one I guess. I think dosing the whole tank is in order because I don't really have an accurate way of guessing who has the mystery illness and who doesn't. I put the two obviously ill tetras in my spare 2 gallon tank but I know that's not a great solution. I bought Tetracycline but am scared to use it until I know how to avoid a tank crash afterwards.