Big fish eat little fish, thats just the way it is 99.9% of the time.
.01% of the time they may not bother with tiny little tetra's, I've seen a large silver aro with a school of tetra's and the owner sad he never bothers them...
Jag's,RD's, oscers etc will pretty much smash them straight away.
Try it with a video camera ready cause i think it will be carnage
ive heard if you raise say an aro on pellet/frozen foods from a fry they wont bother live fish. ive seen lots of asian aros with schools of tetras or barbs, also recall seeing a rhom with tetras.
The problem with mixing small fish in a tank with large ones is that the small ones will likely be stressed by the presence of large ones whether those large fish are predatory or not.
And, giant gouramis will still eat small tankmates.
As mentioned before, 99.9% of the larger fish will eat the smaller, itsy bitsy fish.....Look at my thread:http://www.monsterfishkeepers.com/forums/showthread.php?t=48919....I raised this adult con with quarter sized p's.....Yesterday, or 5 months later, I found him bodyless...I've also tried Arowana/Oscar with tetras, I ended up buying 200 every month and quarantining them before feeding them to the Monsters....Of course this was when I was a "rookie," so I did not know a thing or two on breeding Convicts for feeders....
Well a guy just posted his 18" Silver for sale casue it was rasied with other smaller fish in his tank... And Now he is selling because they are disapearing Ooops!!!