fungus

[Donkey]

I helped my friend set up a 10 gallon tank a couple of weeks ago and gave her some gravel (unwashed) from my tank, as well as some of the filter media from mine to help speed along the cycle.

All of the fish (sunset dwarf platies) have died off from fungus - most likely on one fish and spread to the others as one died several days before the rest of the group. She has 1 platy left, we added some aquarium salt and did a partial water change. The water params are pretty decent, considering the tank is still cycling. I know this one fish left isn't going to make it, but my question is after she dies, should we remove everything from the tank and clean it? ie boiling the rocks and such? What about the filter pad, should it be cleaned as well? I'd hate to lose the cycle we've got going right now.

It's been a few years since I've had to deal with fungus and I'm pretty sure I used maracyn - which my friend does not have the money to purchas right now.

[Aiptasia]

The trick is, figuring out if it was indeed a true fungus that killed the fish, or a bacterial infection that visually mimics "fungus." When was the fungus noticed? After the fish died or before? What are the water parameters and how long has this fish tank been cycling? Ammonia, NitrIte, nitrates? Temperature? Is the last fish alive?

Treating the tank with antibiotics right now wouldn't be a good idea, as they could potentially harm the very beneficial bacteria your friend is trying to grow in their filters and gravel. I would do a fishless cycle if the last fish dies using 100% pure liquid ammonia from the store. We have several articles on how to do it in our articles section.

[Donkey]

The last fish died shortly after I posted this.

I'm not sure of the params now since we live in different houses.

The "fungus" appeared on each fish pretty much the day before they would die. It was white and "fluffy" and appeared mostly on the fish's head/mouth.

I'll help her with the fishless cycle, I've done them before.

What should we do about the tank? I really don't want to harm any bacteria that has already started growing, but I also don't want to chance the disease or whatever staying in the tank and affecting any potential fish.