Like tainted glory said, excess watse is almost certainly the root cause, if you have gray water it is bacterial bloom and that means dead flesh in the tank, if it is green water it is microalgae and it means to much unprocessed fish excrement and urine, either way start with water changes and vaccing the gravel. Add another hang on filter that has has the charcoal replaced with a biomedia seeded with sludge from the one yuo have now. if you have green water also add some cheap tank plants like elodea to compete with the microalgae for nutrients. Feed a little less often and a single feeder at a time, this will also increase the aggression in you P's. Until they get used to that try using feeders only around 1/2 the size of your little friends. All this should help clear things up, can you post a pic?