Just seeing how many other people feel their silver dollars are a little slow in the pea-brain. To be fair, I have 2 schools of silvers. One school of 6 red hooks that are very large and a school of 7 spotted silvers that are about 1/4 of the size. The red hooks are the main culprits and routinely (1x per day mostly) dart wildly around the tank running into the glass tops and walls before ending up in the middle. I would understand if it were from aggression as they are occasionally scared by my larger cichlids- but Im watching the tank now. They were all sitting in the flow of a power head together schooling peacefully, one bumped into the other- that one took of like a bat out of hell cashing into the tank wall which scared the others so one jumped and hit the glass tops and the other got stuck in a corner bouncing from wall to wall????