fungal infection or bad pet store advice?

[MiaRose7]

I purchased a clown loach from a chain pet store. Prior to buying it, I tested my ammonia and nitrite levels (both were excellent). Within a day the new fish died. It had turned a silvery white color.
I brought it back to the store, and they gave me another one. This one lasted 3 days, and then died. When I found it, it had a whispy white coating all over its body. All of my other fish have looked normal this entire time.

Here is my dillemna. This time when I brought it back, they told me I have a fungal infection in my tank. They also tested my water levels. However, I explained to them that they water that I brought in had had a dead fish in it for over 12 hours, so wouldn't the levels be off? The salesperson said it didn't matter. The water levels were dangerously high according to her test.
I went home, and my levels are still fine. But now I don't really trust them.

Should I treat my tank for a fungal infection just in case? Does anyone have suggestions for a type of medicine?

 

[kcormier]

If you have any friends or another lfs to test your water, see if a sample of your water tests well there. It could be that your test kit is expired/defective and that's why you're having issues. If dead fish sit, that white cottony buildup is normal afaik.

lfs = local fish store
afaik = as far as i know

 

[thanatos0203]

well when i brought back my puffer fish, she wanted to test the water but said she couldnt because the dead fish changes the ammonia levels

 

[Lotus]

There's really no test for a fungal infection. If the LFS clerk told you she tested for it, she's lying. A fish will not go from healthy to dead from a fungal infection within 48 or 72 hours. It takes longer than that, and you'd see symptoms.

There are really three possibilities for a fish dying withing two or three days:
1. Bad water conditions in your tank. I think you'll need to check with another store or get new test kits to double-check.
2. The fish was already dying when you got it. If it seemed healthy, it's unlikely it died from a disease within a few days.
3. Poor acclimation. If you didn't acclimate it well, and it's a more sensitive fish (and your water is different than the LFS water) then the shock may have killed it.

I highly doubt it's a fungal infection, and I don't think you should treat. For one thing, fungal infections are fairly rare in aquaria. It's more likely to be a bacterial infection, if anything. A healthy fish will not normally succumb to a bacterial infection. It's sort of like colds and humans -- if you're healthy, you're unlikely to catch a cold, even though the germs are all around you. If you're stressed, tired or in poor health, you'll catch that cold.