hiya
sorry to hear u have white slug thingies
no idea what it is and dont wanna diagnose cos only read up on finrot/fungus and white spot!!!
here's an A-Z of disases maybe it will give u info on what it is until sumone with a lot more knowledge can help ya
http/www.fishforums.net/index.php?showtopic=59440
hope it's some good???!!!
least if the last link is not helpful least u can rule out those on there
maybe try this one
http/www.fishdoc.co.uk/disease/diseasehome.htm
good luck