the gar aggression toward other gar species and conspecifics that we are talking about in the earlier portion of this thread doesn't necessarily apply to very young YOY fishes. at very early stages gars are highly prone toward cannibalism and will eat or attempt to eat gars that are only slightly smaller than themselves.
in these cases (very young YOY), gars should only be kept with those of nearly exact same size, and if one grows larger than the other, they should be separated until they are all at the 8-10" range...usually at this point the cannibalistic tendencies die down quite a bit.--
--solomon