20 gal tank - good mix of community fish ?

(06-08-2016, 05:50 PM)Thor Wrote: For example, is the water current too strong?   Is the heat from the heater evenly distributed?    What is your water temperature anyway?
By the way, haven't they eaten anything at all since you got them?  Always stay in the corner?
Please show me a photo or two of the situation.  

Thank you for the quick reply, Thor

I have black gravel and yellowish gravels corners/parts, the heater is above the black and the filter output is above the yellowish. Tetras stay above the black gravel - closer to the heater, I think they feel safer this way. I don't think current is too strong. I have one heater but the last couple of days the heater is almost off all the time - outside temperature is above 80   
Few fish try to bite the pellet passing by but do it only once, not trying to follow the food. Also I've put black sheet of paper on the wall behind the tank. When the Corys are eating then the Tetras swimming closer to the Corys, overall they just hang in the corner, even at the night time, when the lights are out.
I'll post a video when I get good daytime light.