Da fuq is in the water down there that makes them so murderous?

probably not the water causing it...
During the Atlantic slave trade era, Brazil imported more African slaves than any other country. An estimated 4.9 million slaves from Africa were brought to Brazil during the period from 1501 to 1866.[2] Until the early 1850s, most enslaved Africans who arrived on Brazilian shores were forced to embark at West Central African ports, especially in Luanda (present-day Angola). Today, with the exception of Nigeria, the largest population of people of African descent is in Brazil.[3]