Passage: They are generally small fish, with most species being less than 10 cm (3.9 in), and are often brightly coloured. They are distinguished by their large mouths, and the division of the dorsal fin into two separate fins. Most species live in tropical or subtropical waters, where they inhabit coral reefs and lagoons.They are nocturnal, spending the day in dark crevices within the reef. At least some species brood their eggs inside the mouths of the males.

Question: what is the size of the fishes?
10 cm (3.9 in)