Spotted Knifejaw

Spotted knifejaws are members belonging to the middle and lower strata of the temperate and tropical/subtropical coastal fishes. Their preference being to live in more rocky or coral reef waters. Juveniles tend to circle water near drifting seaweed. Water depth ranging in 10–100 m (33–328 ft), which qualify as being in dark states for prolonged periods of time due to the absorption of light by water. Prevalent in the cool Northwestern water of Hawaiʻi, the spotted knifejaws have been reported to reach up to 710 mm (28 in) in length. More popularly found near Kaua'i and Niihau but can also be seen in the Main Hawaiian Islands. They are also commonly distributed in the South China Sea, East China Sea, and Yellow Sea. From November to March of each year, there is water flowing along the Vietnam coast approaching the Peninsular Malaysia centering at 5°N, at a location where there is cold-water inflow making it a suitable rocky habitat and plenty of drifting seaweed for juveniles to attach to.

The fused teeth resembling a beak, enable the spotted knifejaw to prey on hard-shelled organisms such as clams, sea urchins, and oysters. Though there is limited research on specifics regarding dietary habits of the spotted knifejaw, past studies were known to suggest that they were primarily carnivorous fish due to their unique teeth structure. In depth research conducted to find stomach contents of spotted knifejaws, resulted in having large amounts of aquatic algae in the intestinal contents of all specimens collected. The experiment included seaweed, oysters, as well as a strong inclination to plant bait. That same study also seemingly concluded that spotted knifejaws at different stages of growth seemed to prefer a certain type of diet over the other. Juveniles tend to focus more on seaweed as well as zooplankton while adults tend to veer off into larger prey. They had high preferences for cnidarians, chordates, as well as arthropods. Given that their geographic distribution is a vast, their prey preference tends to mirror the different aquatic environments they are in with a correlation in crustaceans and zooplankton as well as phytoplankton. More research is needed in those separate aquatic environments to distinguish between one another and have a more concrete dietary evolution specific to a region of Spotted knifejaws. …