Yup. Sounds like ick. CHeck out MissFishy's page, the "my fish is sick" section. It talks about it. Usually you can beat it by just slowly raising the temp and you can add some salt if you want. See her page for the specific numbers. It is contagiuos, and the other fish may already have it, but it is fairly straightforward to treat. Do you have a pic? That could help us confirm the diagnosis.