Pentapodus caninus is common along the lagoon reef and on some lagoon pinnacles. Maximum length is reported to be about 35cm, although most of the ones we see are quite a bit smaller.
We puzzled over the small, brightly colored ones below for a while. They tend to live rather deep on the lagoon slope and near the bases of lagoon pinnacles at depths of about 25m or more, where the bright yellow color jumps out at you. Since yellow from sunlight is filtered out by the depth where these are found, this must be another case of shorter wavelength bluer light being absorbed by the fish being re-emitted in longer wavelength yellow. According to Fishbase, the juveniles of several species of Pentapodus all look like this. Since we have positively identified adults of only P. caninus at Kwajalein, we assume all the juveniles here are that species.
Not sure of this at all, but I'm tentatively calling this a Pentapodus caninus in nighttime coloration.
Created 25 August 2018
Updated 26 June 2021