Is this dropsy?

[xindulgences]

How to treat my fish with dropsy?
I have a small aquarium tank thats 10 gallons. I have 5 small koi fish in it. I do water changes every month or so, but because school has started, I wasn't very consistent in the water changes. I also add aquarium salt to my tank.

But a few weeks ago, one of my koi fish began to have a raised lump near its cheeks. A few days later, it developed a red sore with a white center on its belly. When another fish developed red sores, I assumed it was an ulcer, so I treated my whole tank with aquarium salt. The ulcers disappeared after a week, but the original koi fish still had the lump. I thought the lump was going to subside but it eventually got worse and I believe my fish has dropsy now, because its scales are sticking up now,but it's not bloated. I have another tank, but it doesn't have filtering and I'm not sure if its okay to quarantine fish without a proper filtering system so should I do a hydrogen peroxide swab?

And recently, the other koi fish that suffered from ulcers too developed a lump on its side and it's scales are sticking up there too. But it looks a little different from the other dropsy-like koi because the scales aren't all over and for some reason I feel like it's scales are falling off... Would this fish benefit from hydrogen peroxide swab as well? Or like, it's skin is rotting or something..

If I were to treat the whole tank with aquarium salt for the dropsy fish, would I be harming the other fish?

thank you so much for the help!

[Honey Badger 1]

Dropsy is not an illness, more like a symptom of an illness. It's often caused by poor water quality. Water changes should be done weekly, not monthly. Aquarium salt will not help. Epsom salt is usually recommended because it will help the fish to release the excess fluids. I don't know the proper dosage for your tank, you will have to look that up online or maybe someone else here will know and post.
Are those fish koi like the ones in the picture below. If they are they don't belong in an aquarium, they belong in a pond.

[xindulgences]

http://www.google.com/imgres?num=10&...9,r:0,s:0,i:98

im sorry. i meant I have common goldfish, not koi x.x

I don't know, but I think my other fish can still be saved. It doesn't have dropsy but it has a rotting patch on the side of its skin...I netted it and I felt the patch, it's soft and mushy and the fish is swimming side to side bumping into the sides of the tank with its head. is it in pain?

[Honey Badger 1]

Common goldfish don't belong in a 10g either and still need weekly water changes to keep their water clean or all sorts of illness and disease can happen.

[xindulgences]

not helping me tho :/

[Honey Badger 1]

Nope, but I am trying to help your fish. Unless they get a bigger tank and more frequent water changes they are only going to get worse.