- The chimaeras, cartilaginous fishes of the order Chimaeriformes, are also sometimes called "rabbitfishes".
|A foxface rabbitfish (S. vulpinus) meeting a longnose butterflyfish (above) in their coral reef habitat|
About 28, see text
Rabbitfishes or spinefoots are perciform fishes in the family Siganidae. The 28 species are in a single genus, Siganus. In some now obsolete classifications, the species having prominent face stripes—colloquially called foxfaces–are in the genus Lo. Other species, such as the masked spinefoot (S. puellus), show a reduced form of the stripe pattern. Rabbitfishes are native to shallow waters in the Indo-Pacific, but S. luridus and S. rivulatus have become established in the eastern Mediterranean via Lessepsian migration. It can be used in the preparation of bagoong.
Description and ecology
The largest rabbitfish grows to about 53 cm (21 in), but most species only reach between 25 and 35 cm (9.8 and 13.8 in). All have large, dark eyes and small, somewhat rabbit-like mouths, which gives them their name. Most species have either bright colors or a complex pattern.
Another unusual feature among rabbitfishes is their pelvic fins, which are formed from two spines, with three soft rays between them. The dorsal fin bears 13 spines with 10 rays behind, while the anal fin has seven spines and nine rays behind; the fin spines are equipped with well-developed venom glands. All rabbitfish are diurnal; some live in schools, while others live more solitary lives among the corals. They are herbivorous, feeding on benthic algae in the wild. They are pelagic spawners. Many are fished for food, and the more colorful species—especially the foxfish—are often kept in aquaria.
In aquaria, they eat a variety of fresh vegetables and algae. Care must be taken during aquarium maintenance and cleaning, as rabbitfishes are often easily frightened and will use their venomous spines in defense. Their venom is not life-threatening to adult humans, but causes severe pain.
In 2007 Kurriwa et al., outlined a way to split the genus—if the scientific community so desires:
- An ancient group containing e.g. S. woodlandi
- Another fairly small group containing, e.g., the S. canaliculatus/S. fuscescens) complex
- The remainder of Siganus, including the foxfaces
Other lineages might exist and make obsolete the somewhat weak distinction between the second and third groups. Also, it is not known where the type species S. rivulatus would fall, hence names for these three subgenera or genera are not established at present.
Hybridizaton has played a role in the evolution of the Siganidae, as evidenced by comparison of mtDNA cytochrome b and nDNA internal transcribed spacer 1 sequence data. Evidence exists of interbreeding between S. guttatus and S. lineatus, as well as between S. doliatus and S. virgatus.
Also, either females of the last common ancestor of S. puellus and the S. punctatus interbred with females ancestral to the main non-foxface lineage, or males of the former hybridized with females of the last common ancestor of S. punctatissimus and the foxfaces, while males of the latter mated with females of the original foxface species.
An individual was found that looked like a slightly aberrant blue-spotted spinefoot (S. corallinus). On investigation, it turned out to be an offspring of a hybrid between a female of that species and a male masked spinefoot, which had successfully backcrossed with the blue-spotted spinefoot.
As noted above, several presumed species are suspected to actively interbreed even today; these might warrant merging as a single species. This applies to the white-spotted spinefoot (S. canaliculatus) and the mottled spinefoot (S. fuscescens), and to the blotched foxface (S. unimaculatus) and the foxface rabbitfish (S. vulpinus). Alternatively they might be very recently evolved species that have not yet undergone complete lineage sorting, but their biogeography suggests that each group is just color morphs of a single species. On the other hand, the morphologyically diverse Blue-spotted Spinefoot (S. corallinus) might represent more than one species; orange individuals are found at the north of its range, while yellow ones occur to the south, and these two may be completely parapatric. Some species of spinefoot have a very painful sting on each of their barbs, but some are a good eating fish.
There are currently 29 recognized species in this genus:
- Siganus argenteus Quoy & Gaimard, 1825 (Streamlined spinefoot)
- Siganus canaliculatus M. Park, 1797 (White-spotted spinefoot)
- Siganus corallinus Valenciennes, 1835 (Blue-spotted spinefoot)
- Siganus doliatus Guérin-Méneville, 1829 (Barred spinefoot)
- Siganus fuscescens Houttuyn, 1782 (Mottled spinefoot)
- Siganus guttatus Bloch, 1787 (Goldlined spinefoot)
- Siganus insomnis Woodland & R. C. Anderson, 2014 (Bronze-lined rabbitfish) 
- Siganus javus Linnaeus, 1766 (Streaked spinefoot)
- Siganus labyrinthodes Bleeker, 1853 (Labyrinth spinefoot)
- Siganus lineatus Valenciennes, 1835 (Golden-lined spinefoot)
- Siganus luridus Rüppell, 1829 (Dusky spinefoot)
- Siganus magnificus G. H. Burgess, 1977 (Magnificent rabbitfish)
- Siganus niger Woodland, 1990 (Black foxface)
- Siganus puelloides Woodland & Randall, 1979 (Blackeye rabbitfish)
- Siganus puellus Schlegel, 1852 (Masked spinefoot)
- Siganus punctatissimus Fowler & B. A. Bean, 1929 (Peppered spinefoot)
- Siganus punctatus Schneider & Forster, 1801 (Goldspotted spinefoot)
- Siganus randalli Woodland, 1990 (Variegated spinefoot)
- Siganus rivulatus Forsskål, 1775 (Marbled spinefoot)
- Siganus spinus Linnaeus, 1758 (Little spinefoot)
- Siganus stellatus Forsskål, 1775 (Brown-spotted spinefoot)
- Siganus sutor Valenciennes, 1835 (Shoemaker spinefoot)
- Siganus trispilos Woodland & G. R. Allen, 1977 (Threeblotched rabbitfish)
- Siganus unimaculatus Evermann & Seale, 1907 (Blotched foxface)
- Siganus uspi Gawel & Woodland, 1974 (Bicolored foxface)
- Siganus vermiculatus Valenciennes, 1835 (Vermiculated spinefoot)
- Siganus virgatus Valenciennes, 1835 (Barhead spinefoot)
- Siganus vulpinus Schlegel & J. P. Müller, 1845 (Foxface)
- Siganus woodlandi Randall & Kulbicki, 2005
- Froese, Rainer, and Daniel Pauly, eds. (2006). Species of Siganus in FishBase. April 2006 version.
- Debelius, H. (1997). Mediterranean and Atlantic Fish Guide. ISBN 978-3925919541
- Taylor (2000)
- Kuriiwa et al. (2007)
- Woodland, D.J. & Anderson, R.C. (2014): Description of a new species of rabbitfish (Perciformes: Siganidae) from southern India, Sri Lanka and the Maldives. Zootaxa, 3811 (1): 129–136.
- FishBase (2004): Family Siganidae - Rabbitfishes. Version of 2004-NOV-22. Retrieved 2008-AUG-31.
- FishBase (2006): Siganus species. Version of 2006-MAR-14. Retrieved 2008-AUG-31.
- Kuriiwa, Kaoru; Hanzawa, Naoto; Yoshino, Tetsuo; Kimura, Seishi & Nishida, Mutsumi (2007): Phylogenetic relationships and natural hybridization in rabbitfishes (Teleostei: Siganidae) inferred from mitochondrial and nuclear DNA analyses. Mol. Phylogenet. Evol. 45(1): 69–80. doi:10.1016/j.ympev.2007.04.018 (HTML abstract)
- Taylor, G. (2000): Toxic fish spine injury: Lessons from 11 years experience. J. South Pac. Underwater Med. Soc. 30(1). PDF fulltext