38 Gallon Stock

Before anyone says that they are not just mbunas i already know that.
2 Yellow Labs
2 Clown Loaches
2 Lethrinops Albus
2 Haplochromis Ahli
3 Cynotilapia Afra
Unfortunately i'm having a few agression problems, my largest hap ahli is charging at every fish who is smaller than he is, which then provokes some others into getting agressive to the guy the hap is picking on. The only guy who stands up to him is my largest Cyno, is this agression just because they are smaller than he is or is there a problem with the types in my tank. I turned the heater down to 77 degrees to hopefully bring the agression down. My largest lethrinop is getting picked on the most which is really bugging me cus he doesn't even bother with anything going on around him he just sits in one spot, gets chased/attacked, and then finds a new spot for 2 mins.

i dont think it has anything to do with the temperature...how many gallon tank? and hiding places?

38 gallon tank, got quite a few hiding spaces. I think they were still kinda edgy cus i just put them in recently. The aggression has gone down already. They should be fine, my largest lethrinops found a flat rock far from the caves and he just hangs out over there. thanks for replying. ill post more if anything comes up but i think there okay now.

34 gallons is that 128 liter? what are the dimensions?

36"x12"x18"

I went and bought some more fish to hopefully bring down the aggression and it seems to be working. Here is the list(most likely finished):

3 Yellow Labs
2 Clown Loaches
2 Lethrinops Albus
2 Haplochromis Ahli
3 Cynotilapia Afra
2 Lethrinops Letrinus
3 Pseudotropheus Zebra "Red Top"