When I kept mine in a 150 gal tank, I didn't consider them aggressive by normal Central Amer cichlid standards, and they spawned in that community cichlid tank. At the time the male was approx 8"+ and the female approx 6".
I would imagine if you were to cramp them, the scenario may be totally different.
When diving with them, I never saw any overt aggression (even against the schools of live bearers), but if you notice in the video, many individuals are a bit scarred up.