i had the same problem with my silver. the silver would just keep on trying to attack him and try to take nips at him. the silver is about 16" and the jar is about 9". i thought that the jar would end up beating him up, but it was the other way around. i guess my silver rules the tank. btw i moved the jar to another tank, so that he wouldn't end up dead. oh well i guess i can't put them in the same tank.