Featherfin cichlid (Cyathopharynx furcifer) protecting nest in Lake Tanganyika

This male featherfin cichlid (Cyathopharynx furcifer) built a nest out of sand on top of a boulder, and is now protecting it against perceived intruders. His colors are dazzling to attract a mate, but when I swam by he would turn grey and put his fins down instantly, as if a switch was flipped. I set the camera up near his nest and swam away to record this footage. Filmed with gopro 5 near Kigoma, Tanzania