Suggestions on fishmates

[LaDama6589]

I have 4 glow tetras, 1 angel, dwarf, guppy, and a pleco... So I know my fish need some of there own kind but any other suggestions on what I can put in my tank? Petco basically thinks you shouldn't mix anything together so I'm worried if I put certain fish in that they will fight or eat each other.

 

[cmw9787]

First, what size tank do you have? And what kind of filtration do you have?

 

[LaDama6589]

Its a 20 gallon tank... And it came with a filter... It says an internal power filter flow rate of 90 gph