Sample Processing
Gut content samples were collected via lavage (stomach pump, Artim et. al 2017), dissection, or feces collection. Fish that were large enough to have surgical tubing (either 6mm or 3mm outer diameter) safely inserted were gut lavaged. They were then returned to the location on reef where they were caught after recovering in an aerated bin of fresh seawater. Fish that were too small to be lavaged were brought back to the lab and humanely euthanized prior to dissection. However, when possible, fish were placed in aerated tanks for ~24hrs and allowed to defecate. Fecal matter was collected, and the fishes were subsequently returned to the same area reef where they were caught. Samples were screened with a dissecting scope. Since their chitinous exoskeletons are not able to be digested, remnants of gnathiids (specifically the heads, Fig. 1), can be reliably identified by any of the sample collection methods detailed above.