How do I treat a tank for Cotton Fin Fungus?

[numeroletter]

The other day, I got a betta from Pet Supplies Plus, who had just received a bad batch of bettas (which both they and I were unaware of at that time). I noticed a small lesion on his side, but I didn't think much of it, thinking that it looked like the cancer lesion one of my previous bettas had had, which hadn't affected him much in his youth. But it turned out to be something much worse. Within 24 hours (by the next evening), he was absolutely covered with what I believe to be cotton fin fungus. I immediately isolated him and asked the people at PSP for advice the next morning (today), and they treated him with everything they thought might work, then graciously allowed me to take him home, as I wanted to be there for him no matter what happened. Sadly, this afternoon, little Blue Jeans the betta died, as the fungus was just far too advanced to save him.

However, I'm now worried about what to do now with my tank. Blue Jeans was in the tank for about 24 hours, which means the fungus has been in the water. I have a little baby bristlenose pleco in the tank, so small that he's only about an inch long, and I'm really concerned about him potentially contracting the fungus since he's so small. The people at PSP suggested doing a 100% water change, rinsing the rocks and tank ornaments, and replacing all the filter media, but I'm worried that such drastic measures would be a shock to the little guy's system. But I'm also worried that if I don't do that, I won't be able to put another betta in once I find one I like, since I wouldn't want the new betta to contract the fungus either.

What measures can I take to try and eliminate any traces of the fungus from the tank? I'm really concerned about it being present.

(I have a 5.5 gal tank with an AquaClear Power Filter, 4 anubias plants, and a moss ball, in addition to the bristlenose pleco.)

 

[numeroletter]

Update:
Just checked my parameters...
pH: 8.0
Ammonia: 0 ppm
Nitrite: 0 ppm
Nitrate: 5 ppm

 

[charliebankston]

What did they treat him with?

 

[numeroletter]

They treated him with antifungals, antibacterials, aquarium salt, and anti-ich treatment. The only one I know the brand name of is Pimafix, which is an antifungal. We know it wasn’t ich but they gave him the ich treatment anyway since he seemed itchy and they thought it might help with that. Luckily, I never put him back in the tank since he went downhill so fast once I got him home, so none of the medicine is in the tank proper.

 

[charliebankston]

Pimafix and melafix are more of an antiseptic, not really a curative. They help prevent more than anything. Salt won't do as much for fungal as well as it works on parasites. Ich med like hikari ich-x and kordon rid ich plus are great fungal meds, besides for ich

 

[numeroletter]

Ich med like hikari ich-x and kordon rid ich plus are great fungal meds, besides for ich

Ah, I see. Are you of the opinion that I should treat the whole tank with one of those ich meds? As stated in the original post, the fish that was infected has since died. But there is another fish living in the tank, and although he hasn't shown any symptoms thus far, I do worry since he's so small and vulnerable. Plus, I want to eventually be able to add another betta in, and I wouldn't want the new betta becoming infected.

 

[numeroletter]

Update: After doing a bit more research, I think what he had was actually columnaris. I still have no idea what to do with my tank, though.

 

[charliebankston]

Update: After doing a bit more research, I think what he had was actually columnaris. I still have no idea what to do with my tank, though.

Oh OK, columnaris is a bacterial infection. Hard to treat due to it not being seen easily until it's progressed. It's only really treatable with antibiotics. I'd watch this one for a day or 2, might be OK. You can add some melafix to the tank if you desire. It might help kill any bacteria in the water column

 

[charliebankston]

Update: After doing a bit more research, I think what he had was actually columnaris. I still have no idea what to do with my tank, though.

Don't beat yourself up over it btw, unfortunately columnaris has a very high mortality rate