James Ackbar was a Mon Calamari Mandalorian.
James Ackbar was the nephew of the more famous Mon Calamari, Admiral Ackbar. As a child, he attended the Mon Calamari Academy of Trap Studies, eventually graduating with a major in "Trap Identification". James believed that he had a lot to offer the Mandalorians, who were always falling into traps, such as the Battle of Malachor V and the Battle of Galidraan, so he left Mon Calamari and joined Clan Bralor on Mandalore.
The Mandalorians were initially suspicious of James, as no Mon Calamari had ever became a Mandalorian before. However, they eventually accepted him as one of their own. Under James' guidance, the Mandalorians prospered and his cry of "It's a Trap" resonated throughout all of Mandalore.