Rabbitfish

Lore & Background

The genus Siganus was described in 1775 by Danish zoologist Johan Christian Fabricius, based on notes from naturalist Peter Forsskål's Danish Arabia expedition (1761–67), published by Carsten Niebuhr. The name Siganus is a latinisation of the Arabic name for the marbled rabbitfish in Yemen, Sidjan or Sigian, meaning 'rabbitfish'. Carl Linnaeus had earlier described the genus Teuthis, but the International Commission on Zoological Nomenclature has been asked to suppress that name in favor of Siganus to reflect prevailing usage.

Rabbitfishes have laterally compressed, oval bodies, a very small mouth with incisor-like teeth forming a beak, and venomous spines in the dorsal and pelvic fins. Their pelvic fins have two spines with three soft rays between them, a characteristic unique to the Siganidae. They range in maximum total length from 20 cm (blotched foxface) to 53 cm (streaked spinefoot). All are diurnal; some school, others live solitary among corals. They are primarily herbivorous, feeding on benthic algae, though some species have been observed eating jellyfish, comb jellies, prawns, and bait, suggesting opportunistic omnivory.

Hybridization has played a role in their evolution, as shown by mtDNA and nDNA sequence data. Evidence exists of interbreeding between several species, and one individual was found to be the offspring of a hybrid between a female blue-spotted spinefoot and a male masked spinefoot that had backcrossed with the blue-spotted spinefoot. Some presumed species may actually be color morphs of a single species, while the blue-spotted spinefoot may represent more than one species.

Reader's Guide

Rabbitfishes hold significance as a commercially important food fish in the Indo-Pacific, with catches sold fresh, dried, or processed into fish paste. Their venomous spines, similar in at least three species to stonefish venom, cause painful stings but are generally not medically significant in healthy adults. The genus is taxonomically notable as the only extant genus in its family, with ongoing debate about potential splitting into subgenera or genera based on genetic and morphological data. Hybridization has been a factor in their evolution, complicating species boundaries. Two species have become invasive in the eastern Mediterranean via the Suez Canal, and their gut passage of live benthic organisms (ichthyochory) plays a role in long-distance dispersal of foraminifera. Rabbitfishes are also used in aquaculture and the aquarium trade, and some species have been reported to be hallucinogenic.

Did You Know?

• The name Siganus is a latinisation of the Arabic word Sidjan or Sigian, meaning 'rabbitfish'.
• Rabbitfishes have venomous spines in the dorsal and pelvic fins; in at least three species the venom is similar to that of stonefish.
• Two Red Sea species, S. rivulatus and S. luridus, have invaded the Mediterranean Sea through the Suez Canal (Lessepsian migration).
• Some rabbitfish species have been observed feeding on jellyfish and comb jellies, and others on prawns and bait, indicating opportunistic omnivory.