Cichlids and aggressive behavior are synonymous. While not entirely accurate for all species, many cichlids do exhibit aggressive behavior more so than many of your average tropical freshwater fish in the hobby.
Can cichlid keepers mitigate aggressive behavior? Sure. There are many variables that affect aggression levels, many of which are controllable and which have been scientifically documented. These include light exposure, social isolation, species sex ratios, and parental duty sharing. Another variable is the water temperature. A recent ex situ experiment with Pterophyllum scalare (angelfish – yes, they’re cichlids) revealed that as little as 3° C water temperature changes influence aggression levels, specifically latency to fighting and frequency of aggressive interactions.
Not surprisingly, other scientific studies have shown that slight water temperature changes may induce observed physiological and behavioral changes. For more information about the study on angelfish, see “Water temperature modulates social behavior of ornamental cichlid (Pterophyllum scalare) in an artificial system” in the Journal of Applied Aquaculture.