i have a large tank 300 g 9x3x2 and want to know how many silvers i can keep in there because i letting go of my jardini for the fact he ate a tiger knife fish his size and 3 time more expensive so i have been told silver are not aggressive i was told to keep odd number like 1 3 5 just need a idea how many to order my lfs is placing a order for me today and they are ordering med size 5-7 inch for 30 bucks in the tank right now is 18inch fire eel 10 6 to 9 inch discus a florida gar and a indi