I dont know if someone has mentioned this yet or not, so here I go... great apologies if I am wrong or someone has already noticed this..
First off, a black moor is a goldfish, correct? They cannot live in 10 gallon tanks, and they cannot live with tropical fish as a goldfish needs colder water. It seems like your tank is already alittle overstocked anyways, the last thing it needs is a pooping machine like a goldfish. It may seem now that he is okay, but he is probably the source of the problem and things will only get worse.
You need to get him out of there ASAP, to a bigger tank or to the fish store, because Im sorry, but a goldfish is just too much for an overstocked 10 gallon. He is probably already stressed by the warm temperatures, and if you kept it cold, it is the cold temperatures that are stressing out the other fish.
Fish get ich (or any other disease or parasite for that mater) when they are so stressed that their immune system lets its guard off. The water quality probably isnt that good if a goldie is in a 10 gallon, even by itself, unless you do like 25% - 30% water changes everyday. So after you fix the goldfish problem, Id do a very generous water change - but not too much; as that can make things worse. Then choose a nice ich medecine, like Rid Ich or Quick Cure. Add the dosage it prescribes on the bottle, along with the removal of the carbon in the filter, and regular water changes and you will be fine.
You need to find the problem that started the mess before you go and try to fix it, otherwise it will just continue to happen.
I may have been totally wrong.. so correct me if I am..
Anyways, good luck!
Dakota