I used to keep a heavy fish load in my tanks but I got obsessed with aquascaping and it became hard to clean the tank with complete plant cover so I got rid of a ton of fish, Not to mention the plague that is Camillanus worms killed a lot of my fish.
38g used to have
4 3"discus
30 red eyed tetras
10 oto
2 SAE
38g now
3 small angels
2 male apistos
4 FM apistos
10 oto
the bichirs are fairly small at the moment and aren't giving any trouble. i will hav to transfer them soon to avoid any smaller fishes from being eaten. they grow to about 18"-20".
I use Malaysian Trumpet Snails to keep my substrate clean in my planted tanks. I only do a gravel vac when I pull everything to do a total re-scaping, or when I have to use Binox.