The fighting bull is characterized by its aggressive behavior, especially when solitary or unable to flee. Many are colored black or dark brown, but other colorations are normal. They reach maturity slower than meat breeds as they were not selected to be heavy, having instead a well-muscled "athletic" look, with a prominent "morrillo", a complex of muscles over the shoulder and neck which gives the bull its distinctive profile and strength with its horns. The horns are longer than in most other breeds and are present in both males and females. Mature bulls weigh from .