Blue Hippo Tang keeps getting ich.

[joe pooh]

i had left the tank fishless for 8 weeks. Quarantined all fish for 3 weeks and treated for ich before introduction to the tank. this is what i dont understand.

if ich is a parasite and i starved it in the tank and killed it in all the fish, where did it come from? Even if the water quality was bad (it is not) the ich organism cant come out of thin air...

At this point i only have 1 10 gallon quarantine hospital tank so i cant take all the fish out for 8 weeks.