I HAVE 6 DISCUS 2 FUJI REDS AND 4 TURQUOISE CHECKERBOARDS... I USED PRAZI-PRO ON THEM WHEN I FIRST GOT THEM AS A PRECAUTIONARY (ABOUT 7 WEEKS AGO)... THEY WERE DOIN GOOD TILL LAST WEEK.. 3 OF THE TURQUOISE ARE HUDDLED IN THE BACK CORNER OF THE TANK, WITH LOSS OF COLOR AND NOT EATING.. I NOTICED WHAT APPEARED AS A WORM( APPROX. 2 INCHES LONG ROUND AND WHITE IN COLOR) WHAT SHOULD I DO TO TREAT THEM PRAZI PRO AGAIN????