Are your affected fish sucked up, or skinny? Normally an affected fish will still eat (unless it is really sick and usually too late), but the parasites take the nutients from the food eaten and not allowing them to abosorb the nutrients and they start getting skinny. I have also found that i.p. will often times allow for a secondary infection, like cloud eye. Now if your fish is sucked up and has a secondary infection you very well could have i.p. if that is the case i can recomend some meds. and effective ways of administering them, just let me know. Just keep an eye on them white stringy crap is not a definate idicator of i.p. but is a sign.