Water changes. QT the affected fish(es) and do daily 50% water changes and see if that helps.
Agreed. Nothing works as well as crystal clear water. It does take time and i understand you want to get rid of it RIGHT NOW (as i have felt with other diseases and everyone else has here on the fourums) but it does take time. As long as you are patient and continue those water changes it will be gone before you know it.
My fish also has cloudy eyes is there a chance he can die from fin rot also the fins are reddish
Cloudy eyes sounds like popeye. Reddish fins sounds like ammonia burns.
Can you tell us your tank size, stocking, and parameters?
EDIT: And yes, he can die from finrot if the rot spreads to his body.
I have him in a 55 gallon with a pleco and corydoras
What kind of fish are we talking about? You never specified. If it's a common pleco, they create massive loads of waste and should be rehomed. Is your tank cycled?
I think it's cycled a gold doted pleco (L001)
A cycled tank has 0 ammonia, 0 nitrite, and ideally <20 nitrates. If your tank isn't cycled, that explains the problems you're having.
How do I know my water is crystal clear and I have never done water tests ever
You need an API Freshwater Master Test Kit.
Do you know about the nitrogen cycle? You won't be able to tell if the water is toxic by looking at it. It can be crystal clear yet deadly.
How much does the cheapest cost I'm only 12 years old so I don't have a lot of money
Hmm I think it is $20-$30
Extremely necessary for fishkeeping.
That's vary cheap I'm thinking about getting new fish can fin rot be contagious and what do you recommend doing right now I only have a half gallon tank left that is unused and I never quarantined a fish
You'll at least need to rehome either the goldfish or the other fish, as the goldfish isn't temperature compatible with the others. If it were me I would try to rehome the goldfish, then work from there, adding some schooling fish to what you have. But you wanna research the Nitrogen Cycle and look up requirements for any fish you plan on getting. The test kit will help you know what's going on in your tank. If your tank isn't cycled, and you can get your hands on Seachem Prime, that will help a ton with fish-in cycling.
You'll want to rehome one or the other and get your test kit and figure out if your tank is cycled or not before you get any additional fish.
Why do I have to rehome the goldfish is it contagious
I don't know if it's contagious, but either the goldfish has to go, or your other fish have to go. The goldfish is used to cooler water temperatures while your other fish are tropical and are used to water temp in the high 70s or so. Do you happen to know what temperature your water is? Since the goldfish is sick and not the other fish, I am going to assume that the temperature is in the tropical range and that is why your goldfish got sick.
Separate names with a comma.