When it comes to marine fish that earn their keep from the standpoint of visual interest, general ruggedness, and utility in the aquarium, few species can compete with the foxface rabbitfish (Siganus vulpinus). If provided adequate housing and an appropriate diet, this species is even well suited to beginners’ tanks. What’s more, S. vulpinus gives any tang a run for its money when it comes to cleaning up irksome algae.
Hailing from the Western Pacific, S. vulpinus is laterally compressed (flattened from side to side) with an elongated snout that gives the species a somewhat fox-like aspect. It’s a cheery bright yellow over the rear two-thirds of its body (approximately), giving way to a white base coloration on the anterior third. A black band extends upward diagonally from the tip of the snout to just before the first dorsal spine. The chest area is also black. When stressed, this species can rapidly take on a mottled coloration.
It’s noteworthy that S. vulpinus, in common with all its congeners, possesses sharp, venomous dorsal and anal spines, which are capable of inflicting a nasty, painful sting. The utmost care must be exercised when transferring specimens, working in the tank, etc. These spines are typically used only defensively, so you don’t have to worry about your foxface attacking your hand. Nonetheless, it’s very possible for careless handling or relaxed vigilance to result in a sting.
If a sting should occur, seek medical attention immediately. As far as I’m aware, the most common symptom of a foxface sting is severe pain (I can’t speak from personal experience), but different people can react to venom in very different ways.
Foods fit for a foxface
Though S. vulpinus is omnivorous and will happily accept small, meaty food items, such as mysid shrimp, its captive diet should consist primarily of green matter with occasional meaty offerings. Good options include dried marine algae sheets, commercial frozen herbivore formulations, and spirulina flakes or pellets. Occasionally soaking dried foods in a quality vitamin/HUFA supplement before feeding will help to fill in any nutritional gaps. Of course, many forms of live algae growing in the tank will be eaten with gusto, as well.
Recommended tank size
An aquarium in the range of 75 gallons is commonly recommended for this species. However, I would advise going with something quite a bit larger—more along the lines of 125 gallons—as minimum housing. S. vulpinus can grow to exceed 9 inches in length and needs a decent amount of swimming room to boot. A 75-gallon, while suitable for younger, smaller specimens, just doesn’t provide adequate long-term accommodations for a foxface in my humble opinion.
Tankmates and reef suitability
When it comes to fish tankmates, S. vulpinus doesn’t create much in the way of compatibility issues. Foxfaces are usually indifferent to most other species, and other fish species—even relatively aggressive and predatory ones—tend to leave them alone out of respect for those venomous spines. Conspecifics will squabble, however, so it’s best to keep only one foxface per tank.
With respect to inclusion in reef systems, the best advice is to proceed with caution. S. vulpinus isn’t a significant threat to corals, but, like many grazers are prone to do, it may nibble on fleshy coral polyps.