Massive die off

[JPKeenan]

So my one tank, all the water params are good. But the fish are dying.

So I am going to try to save the fish but will re-do the tank. I am going to replace the gravel with sand soon. I am not sure why they are dying. I do not want to take the fish out and put them in a healthy tank if they are sick.

I have an extra sponge filter that has been in another tank. When I change the gravel to sand I will add the sponge filter and clean the HOB with bleach. I will also scrub down all the decorations I have with bleach. Of course I will moniter the water and do PWC all the while while the BB builds back up in the HOB.

I just know that with some of the fish when I got them after coming home from work or waking up (the dead ones). They had a white hairy stuff on them so I am thinking fungal infection.

Any suggestions on cleaning the tank up?

 

[Floyd R Turbo]

What size is the tank?
What kind of fish do/did you have?
What filter do you use?
How often do you do water changes?
How long has the tank been running?

Yeah the white hairy stuff is a pretty good indicator of fungus. I had a tank of cichlids that died off all within a few days, but that was my fault - neglected to maintain the tank.

 

[JPKeenan]

water params are all good. I do a 30-50% water change weekly. It's a HOB filter Aquaon or similar price range model.

Trying to think I had the similar looking fungus on some driftwood of teh same batch that was soaking.

Errr, loosing another one as I type. Platies and danio were in this tank. Doesn't look like an external growth but his colors seemed frosted (faded).

I want to save the fish, but also want to know what to do to get it ready to cycle again (if the fish die).