Latin name

Bathytroctes macrolepis

Other Name

Largescale slickhead

Bigscale smoothhead

Largescale smoothhead

Koefoed's smooth-head

Identification

Bathytroctes macrolepis has a moderately elongate, fusiform (spindle-shaped) body that is compressed at the rear. The head is large, making up 33-40% of the standard length, with a sloping or straight upper profile. The snout is long and bluntly pointed, being approximately equal to the eye length (23-31% of head length). The eyes are large and lateral. They are directed upward and to the sides, allowing it to see the silhouettes of fish and other objects swimming above it against the faint light penetrating from the surface. The mouth is terminal and ends under the center of the eye. Both jaws have a single row of teeth, and the roof of the mouth may have teeth in the center and on the sides, or it may be toothless. The tongue is usually without teeth. Gill rakers are long and slender, numbering 20-22 (4-6 on the upper arch and 14-18 on the lower). The body is covered with smooth scales (38-49 in a longitudinal series), while the head is scaleless. The species lacks a swim bladder. The lateral line is present.

Features of Fish Fins

All fins lack spines. The dorsal and anal fins are positioned at the rear of the body. The dorsal fin has 13-15 rays, and the anal fin has 11-13 rays, with its origin located under the last three dorsal fin rays. The pectoral fins are small and positioned low on the side, with 11-13 rays where the upper rays are longer. The pelvic fins are located towards the rear of the abdomen, before the origin of the dorsal fin, and consist of 7-9 rays and a splint bone. The caudal fin is forked. There is no adipose fin.

Fish Colouring

The body of Koefoed's smooth-head is likely dark brown or black in color, which is common for fish inhabiting the deep ocean.

Distribution

This species has a wide, circumglobal distribution. It is found in the Atlantic and Eastern Pacific oceans, with records from the Bay of Biscay southward to Namibia, including the Azores and Madeira islands, as well as the Gulf of Mexico.

Habitat

Bathytroctes macrolepis is a marine, benthopelagic species that inhabits deep waters. It is typically found near the bottom but can also occur in the water column over soft substrates. Its depth range is extensive, from 1,100 to 5,850 meters, though it is usually found between 2,800 and 3,300 meters.

Size

This species reaches a maximum length of approximately 40-45 centimeters (about 16-18 inches).

Behavior

Koefoed's smooth-head is a bentho-pelagic species, meaning it swims and feeds in the water column just above the bottom. As a resident deep-sea fish, it is found in the bathypelagic zone, far from the shore over the continental slope and abyssal plains.

Food and Feeding Habits

This species is a carnivore. Its diet likely consists of a variety of prey, including bony fish, mobile benthic crustaceans (like shrimp and crabs), pelagic crustaceans, and mobile benthic worms.

Reproduction

Koefoed's smooth-head is an egg-laying species. The eggs are pelagic, meaning they float in the water column, and the larvae are also pelagic. Specific details about its spawning behavior are not well documented.

Fishing

This species is of unknown importance to commercial fisheries, meaning it is not a targeted catch. It is rarely encountered, likely as bycatch in deep-sea nets.

Relationship with a Person

Koefoed's smooth-head is considered harmless to humans. It is listed as Least Concern on the IUCN Red List, indicating that the species is not currently facing a high risk of extinction in the wild.