White fungus on scats

[johnny potatoes]

You could use a combination of Malachite Green & API Triple Sulfa which is IMO the best treatment because it will not only cure the Sap it will also provide protection against any secondary bacterial infection. Another option is API Fungus Cure which will also work (3 mg of Malichite Green and 30 mg of Acriflavin) but I'm not crazy about using Acriflavin if other options are available. Mardel Quick Cure (Malachite Green, Formalin) is a third option.
My concern here is you have an ammonia reading in your tank which indicates it's not fully cycled or the added bio-load has caused a mini cycle. You should do a 50% water change and remove any uneaten food before starting treatment. Do not add meds within the first hour of adding any redox reducer (water conditioner) as it will severly reduce the effectiveness of the MG. You could also treat in a hospital tank but if you do keep the main tank salted to help prevent any other fish for becoming infected. The ammonia is a concern so you have to increas the bio-media or add additional filtration to handel the increased load on the system. Any additional stress on the fish will compromise the immune system and allow this to take hold where it would otherwise not be an issue. Hope this helps.

Thanks for the info on the meds. The ammonia is coming from my tap water, ( .5 ppm as of last night but lately it's been 1 ppm) of course I treat with prime for the whole volume of water with each water change. My understanding is that it detoxifies the ammonia but it still remains in the water. Also I did notice that one of the scats dorsal fin looked messed up as soon add I put them in the main tank, I assumed that was from being caught in the net when I picked them up and really didn't look that closely at it at the time. When I came home the next day all four scats had this fungus on them. I switched some things around and put them in there own tank so they wouldn't pass this on to the other fish. Water params are very similar in both tanks with just the ph .2 different. Also I listed the params for the tank they are in more not the tank I first put them in, again both are very similar. Anymore input on the ammonia in tap water issue? I have asked the question several times before and have been told I would be okadd long as I add prime for the whole volume of water.

40ppm nitrate is considered to be stress zone for many fish, and the scats may have not brought the spores in with them.
The spores may have been in your tank already, but your other fish may have an immunity, because they have grown accustomed to your water.
The high nitrate levels and moving, could in fact, trigger the new fish enough stress to become infected with already existent opportunistic pathogens.
And then in time overwhelm the immunity of the original fish in the tank.
You do not list salinity in your parameters, and scats are a primarily brackish water fish, and prefer a salinity of at least 3ppt, higher is probably better. As scats age, they are best in almost full salinity sea water.
And bringing the nitrate level to below 20ppn with regular partial water changes, is standard good practice

Thanks for your reply as well, I'll do a better job of keeping up on the water changes. I will also look into the salinity issue for the future. Can you please read my response to aquanero above? Anything to add to that would be great. Thanks

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