i have had them like this for 2 years and this is the first instance of something like a disease happening, im not going to seperate them, i know usually it is bad to have tankmates but most of my goldfish are big and the small ones are feeders so i dont mind losing them. Honsetly i think i have a special case here.
Personally, I don't feel goldfish are a good species to mix with amphibians based on some of the reasons posted above, but if you are intent on keeping fish with your axolotl then I will offer some general advice to that extent based on what I know from working in the fish trade.
The first thing to concider is that 90% of fish medication will be harmful to you axolotl. They are designed to be used on fish only and anything that says it should not be used with inverts is a double no-no. Many ich medications, in addition to containing malachite green and formalyn also contain a good amount of salt. So you will need to be careful there. In the aquarium trade there are different methods for dealing with ich:
1. Adding copper to a system - you can't do this with an axolotl
2. Adding general ich medication to the system - you can't do this with an axolotl
3. Raising the temperature to kill off the parasite - you can't do this and not kill the axolotl
4. Removing the fish daily from the system and giving it a dip in salt water or formalyn - possibly your best bet. It takes longer to remove the ich and it is not as effective, but it is the safest route. This has to be done in conguction with massive daily water changes to work. 80-90%
You could also fridge your axolotl until you are finished treating the tank (and are sure
all the medication is out). Just note that you still can't use copper. It will leach into the tank sealant and will aways be there.
You should also note that ich, as a parasite, hatches from cysts in the gravel or on the bottom of the tank and then swims towards sources of light to find a host. So blacking out the tank is a good addition to treatment. This also puts the axolotl in the most danger from the parasite since it lives on the bottom. I am not sure if ich is a parasite axolotls can suffer from, but if it is, it is a bad situation for him to be in.
I also want to make a note on two other things since you mentioned them in your thread. Goldfish as feeders, and waste in the tank.
You mention that your ammonia is fine, this is to be expected in a cycled tank. What would be reading high is your nitrate since that is the end product of the nitrogen cycle in a tank. So you should test for nitrates. The kits say 50 ppm is acceptable, if you have ich and an amphibain then no nitrate should be acceptable. Nitrate is not as toxic as ammonia or nitrite, but it still is hard on the system for both axolotls and fish. Also, with goldfish in your system you probably also have high dissolved organics in the water. These also are hard on the system and could be leading to stress in your animals which is what makes them susceptible to disease. If you have had your fish and axolotl for 2 years together, then the fish will have grown and are producing more waste. That means that what was stable before may become an unatable system (Note if your fish have not grown then there is something wrong with your system. No healthy environment will stunt a fishes growth).
The other thing I wanted to mention was goldfish as feeders. As someone that worked in a fish store I can say that I know a lot about those fish. Yes, goldfish are common feeders, yes they can be used, but weigh the risks carefully. Fish classified as feeders have the lowest quality standards in the trade. They come in with parasites, with disease, and with a high mortality. What many people don't see are the large numbers of feeders that die in each order. Much higher than the "normal" mortality rate. Even high end goldfish are shipped with parasites and illnesses. If you are buying small goldfish to feed to your axolotl, keep this in mind. Yes, not all parasites are communicable, but enough of them are. Quarantine your fish or get them from someone that breeds them and knows how to maintain the health of their animals.
Hopefully this information will be of some help to you. As I said I do not thing goldfish make a suitable tankmate from what I know of the fish, but if you are going to keep them together hopefully this information will help you increase your chances of success.