The reefs shelter many nocturnal or strongly cryptic species, among which the holocentridae, apogonidae and the muraena.

Holocentridae or squirrelfishes

The holocentridae or iihi, are fish of average size (from 12 to 25 cm according to the species), which live hidden in anfractuosities of the reefs during the day and which leave their hiding-place to feed during the night. These species are in general rather gregarious, forming shoals of small size.

Their density is difficult to evaluate, but in general it is relatively weak.They can however on certain reefs constitute a significant part of the community.

Apogonidae

Apogons are fish of small size which as the iihi remain hidden in the rocks during the day. The majority of the species are planctophages and can form significant shoals. Undoubtedly more numerous than one thinks it in the communities, they could constitute the preys of many predators because they are rather slow and do not have any particular protection. The densities and the diversity of apogons seem weak on the majority of the reefs.   Apogon fraenatus

Muraenidae

 

The muraena are especially nocturnal. They are little observed because they seldom leave the cavities where they live. The majority of the species are of modest size (less than 50 cm) taking into account their form anguilliforme, however there are some great species (Gymnothorax javanicus) which can exceed two meters length. The muraena all are carnivorous, their preys being either fishes for the greatest species, or shellfishes. The muraena are never abundant on the reefs of Polynesia, the known densities being much weaker than in the western Pacific.  Gymnothorax undulatus