Spotted handfish


The spotted handfish is a rare Australian fish from the family Brachionichthyidae. It is classified as Critically Endangered on the IUCN Red List 2020. It is a benthic fish usually found at depths of 5 to 10 m, with overall sightings varying from a minimum of 2 to a maximum of 30 m deep. The spotted handfish is unusual in that it has highly adapted pectoral fins, which appear like hands and allow it to walk on the sea floor. It has a highly restricted range, being found only in the estuary of Derwent River, Tasmania, and nearby areas.

Description

The handfishes are a unique, Australian family of anglerfish, the most :wikt:speciose|speciose of the few marine fish families endemic to Australia. The spotted handfish chooses habitats based on the microhabitat features. It tends to prefer complex habitats with features such as depressions and ripple formations filled with shells, to avoid predators. Handfish are unusual, small, slow-moving, benthic fishes that prefer to 'walk' rather than swim. Their pectoral fins are leg-like with extremities resembling a human hand. Females are believed to reach sexual maturity after two to three years at lengths of 75–80 mm.

Diet

Currently, little is known regarding their diet, but they have been reported to prey on small shellfish, shrimp, and polychaete worms in the wild. When captive in aquaria, spotted handfish eat mysid shrimp, amphipods, and small live fish. Newly hatched handfish have been observed to do quite well on a diet of small amphipods.

Reproduction

The species spawns sometime during September and October. Females lay a number of eggs varying from 80 to 250 eggs on a variety of vertical objects, including sea grasses, sponges, macrophytic algae, polychaete worm tubes, and stalked ascidians. The eggs are large in diameter measuring approximately 3-4 mm. Handfish have a short pelagic larval period. Therefore, their eggs hatch after 7-8 weeks as fully formed juveniles.

Preservation concerns

The most urgent matter concerning the survival of the species is to address the nuisance threat posed by the presence of an introduced species of starfish, which prey on the fish eggs.