It sounds like your fish could have Ich, a parasite. It's sometimes treatable if you catch it early enough. I recommend isolating that fish and doing a water change to prevent it from spreading to the others.
It sounds like your fish could have velvet, a parasite that normally accompanies "Ich." There are tablets you can buy at places like Petco that will turn your water blue, but will hopefully kill the parasite before it spreads. Also, you can buy liquid copper, which is also used to fight...
It sounds like your fish could have velvet, a parasite that normally accompanies "Ich." There are tablets you can buy at places like Petco that will turn your water blue, but will hopefully kill the parasite before it spreads. Also, you can buy liquid copper, which is also used to fight...
It sounds like your fish could have velvet, a parasite that normally accompanies "Ich." There are tablets you can buy at places like Petco that will turn your water blue, but will hopefully kill the parasite before it spreads. Also, you can buy liquid copper, which is also used to fight...