I would probably use a smaller hospital tank if he is the only one showing symptoms. Just for the sake of containment and keeping medication costs down. I would imagine treating a 180g vs a 10-20 gallon tank would be several times more expensive.
As of now I'm just going to Epsom salt the tank... If it comes down to using meds maybe a hospital tank. But the entire tank might be contaminated if it comes down to it... I hope the salt works!
i would treat the whole tank myself, salt is harmless to most fish at 1 tsp per gallon, actually a benefit to the fish. follow aquaneros advice, he is the local fish doc... if it is hex as someone wrote i would treat with maracyn 2, not so sure it is though... boil some peas and de shell them for constipation.
i think it may be constipation , which would/could be solved with epsom salt or pea's, however we are going on 3 days now and the oscar still isnt eating.. so i cant get it into his system... i hope the salt in the water will help though!...
question, do i need to re-apply the salt, or once its in the water, it stays till a water change?.. thx
And also do a quick search in Google about Oscar with white poop, it will give you a lot of info.
Epsom salt is like a laxative that will help to clear the guts of the fish, same as boiled peas.