I lost three fish in QT last night.

[Humblefish]

Not to derail this thread, but can I ask where this information came from? IME, antibiotics are not particularly harsh on fish, and their pharmacokinetics typically do not rely on redox but rather interruption of specific bacterial processes (e.g. aminoglycosides inhibit ribosomal protein synthesis).

I guess what I mean by harsh is the appetite suppression + lethargy they seem to cause. So the side effects. I've taken fish that were treated with CP (or copper) for 30 days (plus Prazipro), and the entire time they looked great/ate extremely well. And then just for the hell of it transferred that fish into a different QT and dosed just 1 antibiotic by itself (usually Kanaplex or Furan-2). Almost immediately the fish starts acting reclusive, just lays around, eats very little, breathes heavy, etc. Doesn't happen every time but it does occur often. Even after being placed in a DT (no meds) it can take a week or more for the fish's behavior to return to normal after 10 days in antibiotics. FWIW; combining Kanaplex + Metroplex + Furan-2 doesn't seem to make the situation any better or worse, from a side effect standpoint.

 

[sil40sx]

White patches looks like ammonia burn, maybe?

 

[Fenzinna]

White patches looks like ammonia burn, maybe?

While I couldn't read ammonia levels because of prime in the water, I did 50% water changes every 3-4 days.

Last fish died two days after water change. I was barely feeding more than 7-8 mysis at a time twice a day.

 

[sil40sx]

Oh wow, I can only imagine your frustration. It is difficult to pinpoint the culprit. Looks like you already did all you can do. I hope you'll figure out what caused your losses, so it can be avoided in the future.