well,
sharks are moderators of the board, there answers are not the final word, there are lots of people on this board with a wealth of info, Fmarini ansered u question frank, who's has been hooby many years and writes articlles on SWF is highly regarded here for his extensive amount of info he provides to the hobby, you have heard they can get ick and that they are also very hardy and don't get it as easily , u have to read thru the post's sometimes and decide as to how you want to handle your situation, as everyone's case is different ,
to sum up your question:
they generally do not get it but yes they can
if u leave him in then he may or may not get it there is no def way to know for sure