We have 11 fish now, 3 platys, 3 molly's, 3 tetra's, a pleco and a rainbow shark. We do vary their diet, one day it's brine shrimp, one day it's worms (blood worms? they are red), and regular flakes. We feed them what seems like a lot and they devour it in seconds. I know it says only feed them what they will eat in three minutes, and that just seems like SO much food! Thus, we've started feeding them morning and night. How do we know if it's too much or not enough?

The average fish's stomach is about the size of its eye. Count eyes, guesstimate, and feed accordingly. It is always better to underfeed than overfeed.

I feed them more than once a day and they eat everything in 15-30 seconds, they seem to be happy and healthy.

Good pointer on the eye count Tolak, feeding less is better is definitely a good plan especially if you have plants and algae.