The Hatchetfish Family – Sternoptychidae

There are currently THREE members of the Hatchetfish or Sternoptychidae Family, two from the Atlantic and Pacific Oceans and one from the Pacific Ocean, presented in this website:

FROM THE ATLANTIC AND PACIFIC (2):

FROM THE PACIFIC (1):

The Hatchetfish or Sternoptychidae Family, has seventy-three global members that have been placed in ten genera and are found in the Atlantic, Indian, and Pacific Oceans. There are seven species in the genus Argyropelecus and four in the genus Sternoptyx, which are collectively known as Silver Hatchetfish. They are also known as Deep-sea or Marine Hatchetfish and in Mexico as peces hacha. They are small abundant silvery bioluminescent fish that are found in deep oceanic midwaters that are seldom seen by humans. They receive their common name from their body shape which resembles a “hatchet” with the tail base representing the handle.

The Hatchetfish have extremely compressed disc-shaped bodies with a deep keel, large eyes with keen eyesight, a large oblique mouth with small teeth, pectoral and pelvic fins found well back on the body, and a series of photophores along the lower sides of their head and body. Most have a small adipose fin. They are small in stature ranging in length from 2.8 cm (1.1 inches) to 12 cm (4.7 inches). Their anal fin has 11 to 38 rays that may be divided into two parts. Their bodies are covered with silvery scales.

Most Hatchetfish reside in very deep offshore waters at depths between 183 m (600 feet) and 548 m (1,800 feet) and undergo daily vertical migrations moving to shallower waters at night to feed and returning to the ocean depths for protection during the day. They prey on amphipods, copepods, euphausiids, small fish and ostracods. They live sluggish non-mobile lifestyles. They are well-camouflaged due to their silvery color and are able to avoid predation using their series of downward-pointing photophores and their darkly-pigmented dorsal surface. This bioluminescent counter-illumination involves the production of varying amounts of light by each fish to camouflage its silhouette from predators found below. Many species have transparent anal, caudal, and dorsal fins. Reproduction is oviparous with external fertilization that occurs in open water. Offspring are not guarded. Most are short-lived with a lifespan of less than one year. The Hatchetfish are very small, poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.

The Hatchetfish are currently considered of Least Concern, with stable populations over wide geographic ranges, however, these populations are poorly monitored.