I am pretty experienced with fish, but I have never came across this before. We have just bought my Nan some fish(2), and they have been in their tank for three weeks and seem to be settling in well. But just today I noticed one is excreting very long strings of waste, which seem to stick to him for very long periods, around 2-3 hours and then when hes done he goes again. they are on pellets, and sometimes flakes. Any Ideas? Thank You.