Too much anacharis - harmful to fish hibernation?

[frankrizzo]

May be silly question, but is it possible to have too many anacharis on bottom of pond and possible to hinder the hibernation of fish? I purchased several bunches early this season and they have quickly covered the entire bottom of my pond. Have even cut alot of them down and also pulled out some individual pieces from the bunches. It is still basically covered, but I noticed when I "thinned" them out a little bit, the fish went right down and started swimming towards the bottom and through the plants. Before that, they were all swimming above the anacharis. So I wonder if there is too much floor covering and not allowing them to get as low as they want.