HELP SICK GOLDFISH?
"He lives in a 30 gallon tank by himself." So why did you move him to a "sick tank"? Sick fish need stability, changes stress and harm fish in general, stress on a fish that is already sick is even worse! Get him back to his home. Test for ammonia nitrite and nitrate! And add seachums prime and seachums para guard to the water after you test it. Fancy goldfish need a stable temp, and its getting cold out, you may need to get a heater, even though he is a cold water fish. The temp should stay at 70 24/7. He is eating and that is a good sign! You say he only eats off the gravel? then add a small dish and use a turkey baster to place his regular food on it. What is his regular food? it is important to offer a variety of foods to get him a variety of nutrients. You can offer him a tempting treat of thawed frozen bloodworms 2-3 times a month, not the freeze dried stuff though.
Is the water shed, or do you change it a lot? If you change it a lot, then the proper good bacteria can't grow. Go to an aquarium store and ask.
Goldfish, like all other tank bred fish can get so many illnesses and do not really have a long life. If he s struggling it means he has something wrong with him. Unfortunately, there aren t many things you can do to reverse illnesses such as :ICK (look it up). Even if you could fully diagnose an illness in a small fish, it would be near impossible to find anyone to treat him. As long as you have him separated from your other fish, they should be fine. This is a part of the fishy life cycle the strong thrive and the weaker ones die off. Sorry to be the bearer of this information, but you have to just accept that its his time and move on.