hey jolly!
yes that may be it, they do dart, but also so do puffers, they also move quickly, especially when playing around, or scared, but they are fine with the otto i have now, i will just keep him until algea gets really bad, if it does..... thanks for all your help, this thread can be closed now, i have resorted to keeping my otto i have now, and getting a CO2 system to prevent algea as well