Possibly looking for a change in my fish lineup..

I'm thinking about swapping out my Green Severums. I'm looking for something that will be a mid tank swimmer, personality would be nice and definitely does not eat live plants. Schooling or a pair would be fine, I'm not looking for a spawning pair, I'm tired of the aggression in the tank every couple of weeks. Any ideas?

My tank is a 125g with an FX5.

Stock list is:

4x Green Severums - 5" - 7"
3x Endlicheri bichirs - 5" - 7"
2x Syno decorus - 6" - 7"
1x Megalodoras uranoscopus - 4"
1x Bulldog Pleco - 2"
1x Hoplo catfish - 6"