blue gourami's aggressive?

I have 10 gouramis total, they will occaisionally chase each other, but I have never found any torn fins or dead fish as a result of it. My rule has always been to buy them in pairs (1 male, 1 female) so there is little competition between them.
 
as of this morning, i've had 6 neon tetras dead (all torn up) and 2 bleeding hearts dead...i'm thinking from the blue gourami's!
 
If given enough space, gouramis are pretty mellow fish who normally just chase other anabantids when they get into each other's territories. Stick a few into a small tank where they can't establish a territory for themselves and they may fight.

They normally aren't very aggressive to other fishes though they are known to push around smaller fishes, but you never know what happens when you stick a fish into a small tank. How big is your tank and how long has it been set up?
 
i have a 46 gallon tank that has been set up for about 4 months now.

first of all, i think i was a little overstocked so i don't think it gave the gourami's much space. i had a school of neon and bleeding heart tetras, plus 3 buenos aires tetras along with some guppies.
 
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