I recently added 2 green tiger barbs to my tank that already included 6 other healthy fish, all who currently show no symptoms of ich. i got the green barb yesterday, perhaps i didnt notice it but now i see a single white dot on the tailfin. This is the sole dot or symptom on the fish and the entire tank after observation of one day. Does that single dot mean ICH? i have taken preventative measures since i have a bottle of formalin treatment, but should i be more worried about an outbreak of the disease?