Well, it could be, and could be not. You need to observe the fish closely since only one has the symptoms so far. But Ich is contagious so if one has it, others may get it as well. If the condition worsens daily and the fish gets more white spots it is likely Ich. Waiting with diseases is not good but then again, you don't want to misdiagnose. It would be best if you referred to the Disease Chart (on the top of this board) and made sure the symptoms are most likely of Ich.
Besides, what are your
ammonia,
nitrite, and
nitrate readings? What other fish and how many do you have in your 10 gallon tank? How long have you had the tank? What's the temperature?
After you've determined that the fish indeed has Ich, there are many over-the-counter Ich medications at fish stores. The ones I know are Mardel Labs' CopperSafe and Maracide. When treating, it's best to gradually increase the temperature to at least 82F (some people would go even higher than 82F). If you don't have any salt-sensitive fish, you could also be adding aquarium salt during the treatment at the rate of 1 tablespoon per 5 gallons of water. When adding salt, though, mix it with a cup or two of tank water first, dissolve it completely, and then slowly pour the solution to your tank.
