sick fish caused by dead plants???

Question
Thanks! I was advised by a friend to freeze the fish that are sick and start over. I was advised to remove the fish and put bleach in the aquarium with the gravel and rock and let it soak. How long do i leave it in there and how do I make sure all the bleach is out of the gravel and everything making it safe to refill it? Is this even a good idea?
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Followup To

Question -
I have a 20 gallon aquarium with 5 tetras with fin rot and one also has a cataract.  I have 3 banana barbs one with mouth rot.  I have 2 albino tiger barbs one with that turnes tail up and nose down and the other with fungus around his gill. My black red tailed shark and 1 albino tiger barb, and 1 banana barb have died.  I do have 1 dwarf blue guarami and 1 dwarf chocolate guarami which i have removed into a bowel in some safe "ditry water" from a friend. My nitrites are elevated and so is the ammonia. The ph i just tested is perfect. I bought some sword grass a month ago that discentigrated within one week. I removed the rotting leaves, but did not thing to remove the root system once all leaves were gone. Could the rotting roots cause the nitrites and ammonia to go up causing the fish to stress making them susceptible to all kinds of diseases/fungi...?  I have tried to treat the tank 2 different times each time using a different medication over the past 3 weeks and nothing helps.  Should i remove the infected fish and euthanize them, then disinfect my tank, and start all over again?

Answer -
Hello Sarah-

Wow, that sounds like a mess.

So, the gourami are not sick? It's good that you removed them. First off, take all the fish out of the main tank. Drain the tank, trash the plants, scrub the walls, and soak the gravel in warm water. Refill the tank with fresh warm water, and be sure to treat it with conditioner. Then add gravel, and wait for everything to settle.

Float the sick fish, then reintroduce them. Keep the gouramis separate for now. Add a dose of Maroxy, to treat the fungus, and a heavy dose of QuickCure, to treat everything else. Also, add some Cycle to the tank to help get the good bacteria up and living and reduce the ammonia/nitrates.

Don't reintroduce the gourami until all the fish have been healed or have died...I'd say after a week or so. Be sure to keep them healthy in the bowl, or they won't survive being isolated.

You can always opt for euthanasia, but do not flush living fish, ever. If you must kill them, place them in a small bowl in the fridge until the water temperature drops low enough to shut down their systems.

Hope this is helpful, and good luck getting your tank back to normal!
-Amber Worman

Answer
Hello Sarah-

I try to steer clear of bleach...If you do want to use it, be sure it's diluted (1 part bleach : 3 parts water.) Let it soak in the tank for an hour, then rinse, rinse, rinse. Then, rinse again. :) Then set the tank out in the sun to allow anything still there to evaporate off. I would not bleach the gravel, however, as it may absorb the bleach and kill all your fish later on.

Hope this is useful,
Amber Worman