Symphodus caeruleus

Symphodus caeruleus is found over shallow, inshore rocky reefs with a good cover of algae which it uses for cover, feeding and nesting. Like many wrasse species this fish is a protogynous hermaphrodite, with sexual maturity being attained by males at a total length of 12 centimetres (4.7 in) and 14 centimetres (5.5 in) for females. This means that the males can still resemble the initial phase or be in their terminal phase after changing sex from a female. They spawn from March to June when the larger terminal males form harems and become territorial, this attracts females to spawn their demersal eggs in the male's nest and the males then provide exclusive care for the eggs. The males still resembling the initial phase, i.e. they look like females, possess larger testes than the terminal phase males and they may attempt to sneakily fertilise the eggs during spawning.^[1]

Symphodus caeruleus was first formally described as Centrolabrus caeruleus in 1999, previously all wrasses from the genus Centrolabrus in the Azores had been identified as the emerald wrasse (Centrolabrus trutta). Later studies showed that this species was not as closely related to the rock cook as thought and it was placed in the genus Symphodus.^[4] The specific name caeruleus refers to the blue colouration of the terminal phase males.^[3]