Blotched foxface
A venomous rabbitfish with a single black spot on its flank.
The blotched foxface (Siganus unimaculatus), also called the blackblotch foxface or one-spot foxface, is a marine ray-finned fish in the rabbitfish family Siganidae. It inhabits coral reefs and lagoons in the central Indo-Pacific. Its body is compressed, with a depth about 1.9 times its standard length, a steep head profile behind the eye, an indentation between the eyes, and a forked tail fin. The dorsal fin has 13 spines and 10 soft rays, while the anal fin has 7 spines and 9 soft rays; all fin spines contain venom glands. Maximum total length is 20 cm.
The fish is bright yellow, with the head and front part of the body white. A black band runs from the mouth to the start of the dorsal fin, and another extends from the shoulder to the chest. An irregular black spot or blotch sits on the center to rear of the upper flanks. This spot distinguishes it from the closely related foxface rabbitfish (S. vulpinus), which it otherwise resembles. The two are sympatric and not phylogenetically distinct; they may be recently evolved species or merely color morphs, and some argue they should be united under the name S. vulpinus.
The species was first formally described in 1907 as *Lo unimaculatus* by American ichthyologists Barton Warren Evermann and Alvin Seale, with the type locality given as Bacon, Sorsogon, on the east coast of southern Luzon Island, Philippines. The specific name *unimaculatus* combines *uni* ("one") and *maculatus* ("spotted"), referring to the characteristic black spot.
The blotched foxface has two disjunct populations. A northern population occurs in the western Pacific from the Ryukyu and Ogasawara Islands of Japan to the Philippines. A southern population is restricted to the Rowley Shoals in the Timor Sea off northwestern Australia. It is found in shallow waters down to 14 m on coral reefs composed of *Acropora* and *Porites*, as well as on coral rubble.
It is herbivorous, feeding on seaweeds. Adults and subadults live in pairs, including same-sex pairs, and these adult pairs appear to be permanent. Reproduction seems to occur at the new moon, when large aggregations form and demersal eggs are laid. Juveniles may gather in large schools. The venom in its fin spines is similar to that of stonefishes, according to a study of a congener.
Quick Facts
- Taxon
- Siganus unimaculatus
Facts from the source article.
Lore & Background
The blotched foxface was first formally described in 1907 as Lo unimaculatus by American ichthyologists Barton Warren Evermann and Alvin Seale, with the type locality given as Bacon, Sorsogon, east coast of southern Luzon Island, Philippines. Its specific name is a compound of uni meaning 'one' and maculatus meaning 'spotted', referring to its characteristic black spot. The species differs from the closely related foxface rabbitfish (S. vulpinus) in possessing a large black spot below the soft-rayed part of the dorsal fin. The article notes that the two are sympatric and not phylogenetically distinct, and though they might be recently evolved species, they may be just colour morphs and should arguably be united under the scientific name S. vulpinus.
The blotched foxface has a compressed body with a steep dorsal head profile and an indentation between the eyes. Its caudal fin is forked. The body is bright yellow, with the head and front part white; a black band runs from the mouth to the start of the dorsal fin, and another black band extends from the shoulder to the chest. An irregular black spot or blotch sits on the centre to rear of the upper flanks. The fin spines hold venom glands, and a study of a congener found rabbitfish venom similar to that of stonefishes.
The species has two disjunct populations: a northern one from the Ryukyu and Ogasawara Islands of Japan to the Philippines, and a southern one restricted to the Rowley Shoals in the Timor Sea off northwestern Australia. It inhabits shallow waters down to 14 m on coral reefs made of Acropora and Porites, and on coral rubble.
Reader's Guide
The blotched foxface is a herbivorous rabbitfish that feeds on seaweeds. Adults and subadults live in pairs, including same-sex pairs, and these adult pairs appear to be permanent. Reproduction seems to take place at the new moon, when large aggregations occur and demersal eggs are laid. Juveniles may gather in large schools. The species is targeted by fisheries using spearfishing and drive-in nets, with the catch sold for food, and it also appears in the aquarium trade. Its venomous spines are a notable defensive adaptation, and the taxonomic uncertainty regarding its relationship with the foxface rabbitfish—whether they are separate species or merely colour morphs—remains unresolved in the scientific literature. The blotched foxface is thus significant both as a commercially utilized reef fish and as a subject of ongoing taxonomic debate.
Did You Know?
- The blotched foxface was first described in 1907 as Lo unimaculatus by Evermann and Seale from a specimen collected in Bacon, Sorsogon, Philippines.
- It has two disjunct populations: one from Japan to the Philippines, and another restricted to the Rowley Shoals off northwestern Australia.
- The species may be just a colour morph of the foxface rabbitfish (S. vulpinus) and not a distinct species.
- Its fin spines contain venom similar to that of stonefishes.
Frequently Asked Questions
What is a Blotched foxface?
The Blotched foxface (Siganus unimaculatus) is a small marine rabbitfish found on coral reefs and in lagoons across the central Indo-Pacific. It goes by a few other common names, including blackblotch foxface and one-spot foxface.
How big does a Blotched foxface get?
It tops out at roughly 20 cm (about 7.9 inches) in total length, so it stays a modestly sized reef fish. Its laterally compressed body has a depth approximately 1.9 times its standard length, giving it a tall, deep profile.
What does a Blotched foxface look like?
It's a vividly yellow fish marked by a single bold black blotch on the flank, a steep forehead behind the eye, a visible dip between the eyes, and a forked caudal fin. The dorsal fin bears 13 spines over 10 soft rays, and the anal fin has 7 spines over 9 soft rays.
Is a Blotched foxface dangerous to handle?
Yes — every spine in its dorsal and anal fins is backed by venom glands, so a careless grab can deliver a painful sting. This venomous-spine trait is shared by all members of the rabbitfish family, Siganidae.
Where in the wild can I spot a Blotched foxface?
Look for it on coral reef slopes and in sheltered lagoon settings throughout the central Indo-Pacific. It's a strictly reef-associated species rather than an open-water dweller.
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