Safely restocking a tank?

[Enbilly]

Hi everyone!

I have a community tank that started with one female betta, 5 false Julii cory catfish, and a school of cardinal tetras. A few months ago a bacterial infection ravaged the tank, and despite medication and my best efforts, all but the betta, and two each of the tetra and catfish passed away. I know the tetra and catfish can't live happily without a larger school, but I'm concerned that introducing new fish, even after quarantine, might leave either the new fish or the current fish prone to diseases the others carry, especially with cardinal tetras being wild-caught. Should I opt for the captive-bred neon tetras, and will cardinals school with them? And how can I safely and ethically introduce new fish? 

[Ken]

I would buy the med trio kit and have it on hand. Then, buy the additional fish you want and put them in the community tank and hit the whole thing with the med trio. Assuming the tank is large enough and established enough to quickly catch up to the additional bioload. Be standing by with a test kit. If that feels too risky or it's smaller tank, then hit the existing fish in the community tank with the med trio and buy, quarantine and medicate small batches at a time before adding them. I wouldn't worry about wild caught if using the meds in quarantine.

Use the med trio as instructed here:

How to Treat Sick Aquarium Fish (Even If You’re Not Sure What’s Wrong)

WWW.AQUARIUMCOOP.COM

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Treating sick aquarium fish can be difficult, especially if you’re new to the hobby or have never seen this disease before. Based on years of experience...