"Aggression levels" refers to the amount or intensity of aggressive behavior someone displays in a situation. It indicates how aggressive or violent a person or animal is behaving. Full definition
However, many other breeds are suitable with the common behavioral trait being a high aggression level. (all-about-great-danes.com)
This breed has a very low aggression level, which means they're fine with strangers and other pets. (topdogtips.com)
They found that the whistles keep dolphins in contact with one another and to coordinate hunts, while the burst - pulse sounds are made to keep aggression levels in check during times of high excitement. (treehugger.com)