The royal dottyback (Psuedochromis paccagenelae) and the royal gramma (Gramma loreto) are two very similar looking fish found in the euphotic zone. many people confuse the two because of their shape, colors, and size.
The first thing you can use to identify which fish is which is that the royal gramma has a yellow to purple gradient in the middle section of its body while the royal dottyback doesn’t. The royal gramma also has a darker shade of purple on its head while the royal dottyback has a more fuschia colored head.
The royal gramma has two distinctive markings on its body, one on the front of its dorsal fin, and the other on its eye. The royal dottyback has more of an aggressive temper, rushing towards other prey or fish, while the royal gramma is more peaceful.