I here that internal parisites (my experiences with ebjd) can travel by mouthing the poop of another. I also here that the parisites do have eggs which can be survive whole tank treatment. So like others said i vacume the bottom very well and take everything out of the tank and give it a rub down with hot water. I also do a water change and clean the glass before i fill it up again with wet warm wash cloth. It seems like its helped me and is what i could figure out through my search on it. Very glad your blue are doing well. It is such a drag when everything starts going wrong and they get sick.
