White fuzz on ONLY the live bearers (guppies and endlers?

[peaceteacher]

Good evening,

The picture is the best I could do. I have been treating my main tank since sunday with the quarantine trio because I have been losing my live bearers about a fish a week (sometimes 2 or 3) for 2 weeks now. Since starting the meds I have lost 3 guppies/endlers  The tank the fish is currently in for the photo was short notice and has been cleaned since. The female was fine this morning but when I got home, I saw that she had a patch of white fuzz on her. A google search says that this is fungus (not sure how it got to this point with the meds in there but regardless) but what I am not sure about is that why is it only affecting my livebearers? I thought they might have been old at first but the fuzz confirms that their deaths were not natural. I also have a female betta, blue kerri tetras, kuhli loaches, a bristle nose and otos in the 40 gal tank. I checked my water last night and found nothing amiss. I am concerned for all my fish at this point and don't know what else to do.

I was reading some online info that said I need to do several major water changes and meds? 

Please advise 

[Colu]

White fuzzy patch can also be Columnaris it's difficult to tell of your pictures if you can get a Better picture if it is Columnaris you want to treat with kanaplex and jungal fungas clear fizz tabs containing nitrofurazone together following this treatment schedule

Edited May 7, 2022 by Colu

[Atomicfish]

I find it hard to figure out why it would only be on your live bearers. usally if its a really a serious sickness everyone would be effected.

[drewzero1]

On 5/6/2022 at 11:27 PM, Atomicfish said:

I find it hard to figure out why it would only be on your live bearers. usally if its a really a serious sickness everyone would be effected.

My hypothesis would be that the livebearers may be less able to fight off the infection... either less happy about the water, or less hardy in general. As far as I'm aware they tend to like the water harder than the other listed fish, but I wouldn't expect that to be a deal breaker for guppies or endlers as much as it might be for mollies. What are the water parameters?

Edited May 7, 2022 by drewzero1

[Atomicfish]

I have too agree with Drewzero1's hypothesis all though from experience livebearers are usally pretty hardy. I also have heard that mollies all though I never did this prefer brackish water.

[peaceteacher]

So my water parameters are as follows. I have now taken all of the guppies/endlers out of my main tank, done a huge water change, and put the livebearers into a 10 gal tank with 3TBSP of aquarium salt. The fish I posted a picture of died and had blood where her gravid spot would be (internal bleeding?). I noticed 2 other guppies/endlers were zombie swimming (swimming in the same spot for days and not eating like they were in a trance) hence why I removed them all.

PH about 6.8 to 7

Nitrite: 0

Nitrate: 25

GH 300 (on the Aquarium Coop test strips basically its at the highest number )

KH 40 (on the Aquarium Coop test strips basically its at the lowest number)

[Colu]

Your kH is on the low side for guppies I would add some crushed coral to help raise your kH