Foxface Rabbitfish
Siganus vulpinus
The Venomous Lawn Mower (9.5 inches / 24 cm). The absolute best grazer for bubble algae. Extremely peaceful, but armed with venomous spines to deter predators.
Water Temperature
24 - 27 °C
pH Value
8.1 - 8.4
Water type
Freshwater
Tank level
Bottom and middle
Adult size
25 cm
Minimum tank volume
>= 300 L
Minimum group
>= 1
GH
15 - 30 dGH
KH
7 - 15 dKH
TDS
295 - 600 ppm
Conductivity
461 - 938 uS/cm
Species description
Geographical Origin and Habitat: Western Pacific Ocean. Frequents reefs rich in branching corals (Acropora) and sheltered lagoon reefs, where it tirelessly grazes the algal cover on the rocks.
Taxonomy and Morphology: Foxface Rabbitfish (Siganus vulpinus). It has an elongated and tubular snout to slip between the corals to tear off algae. The rays of the dorsal and anal fins hide retractable venomous spines.
Social Behavior: Shy but armored. Juveniles live in pairs or small groups, adults are mostly solitary. If frightened, it erects all its spines in a fan and retreats into a corner, becoming an impenetrable "stinging wall" for predators.
Coloration and Sexual Dimorphism: Yellow and Black Warning. The body is a dazzling golden yellow, with a prominent black and white spot/band on the snout that resembles a mask (fox face). When it sleeps or is stressed, it "turns off" the yellow becoming horribly mottled with military brown/gray.
Care, breeding and tankmates
Aquarium Setup: Large marine aquarium (Minimum 120 cm / 48 inches). Lots of well-established live rocks with crevices where it can hide during the night. Avoid overly frantic or aggressive tankmates who would corner it.
Diet and Feeding: Grazing herbivore. Devours the annoying bubble algae (Valonia) and tuft algae, making it very useful. In addition to spontaneous algae, it must be fed heavily with Nori seaweed sheets (fixed to a clip) and vegetable feeds.
Water Quality: Clean and well-oxygenated marine water. It is very robust and resistant to the most common skin diseases compared to surgeonfish, but does not tolerate high nitrate accumulations typical of neglected tanks.
Compatibility and Cohabitation: Reef Safe "with caution". If well fed, it ignores corals. If hungry, it will mercilessly nip the polyps of soft corals (LPS) and giant clams. Excellent with peaceful fish; aggressive fish avoid attacking it because of its lethal spines.
Aquarium Breeding: Never documented in amateur aquariums. They reproduce in nature by releasing clouds of pelagic eggs at sunset.
Risks and Diseases: The Venomous Sting. The dorsal, pelvic and anal spines are connected to venom glands. Accidental stinging during maintenance causes excruciating pain similar to a scorpion sting (to be treated by immersing the part in very hot water to denature the proteins).
Geographic Origin and Distribution
Western Pacific Ocean. Frequents reefs rich in branching corals (Acropora) and sheltered lagoon reefs, where it tirelessly grazes the algal cover on the rocks.
Origin
Tropical oceans and reefs
Fish profile
- Temperament
- Semi-aggressive
- They are remarkably peaceful towards other species and are often considered a "gentle giant" in community tanks. When frightened or sleeping, they exhibit a fascinating defense mechanism where they instantly turn a mottled brown and extend their venomous spines. Extreme care must be taken during tank maintenance to avoid accidental envenomation.
- Diet
- Omnivore
- They are quintessential herbivores that require a heavy daily intake of marine algae and vegetable matter. Provide them with a constant supply of dried seaweed (nori) attached to a clip. They will also happily accept spirulina flakes, herbivore pellets, and occasional meaty treats.
- Life expectancy
- 10-15 years
- In captivity, the Foxface Rabbitfish can easily live for 10 to 15 years when housed in a large, well-maintained aquarium. Minimizing stress and providing a high-quality, balanced diet are crucial elements for ensuring its long-term survival. As a hardy species, it can tolerate minor water quality fluctuations once fully established.
- Adult size
- 25 cm
- The catalog's scalar value is 25 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 25 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Siganus vulpinus (v25.04); male or unsexed record. These figures are not interchangeable: the first is the profile's editorial reference, whereas the second is a published maximum under a specific measurement convention; differences among sources can reflect sex, population, life stage and measuring method.
- Sex ratio
- Solitary
- They should be kept singly unless a bonded, mated pair can be acquired. Keeping two males or two females together will almost certainly lead to severe, potentially fatal aggression. They are also highly aggressive toward other species of rabbitfish.
- Feeding frequency
- Twice daily
- Offer them small amounts of food two to three times a day to simulate natural grazing. A constant supply of nori ensures they do not turn to picking at corals out of hunger. They are very active feeders and will quickly learn to beg for food when you approach the tank.
- Bioload
- The Foxface Rabbitfish creates a significant bioload due to its large adult size and voracious appetite. They constantly process plant matter, resulting in a continuous output of biological waste. A well-established aquarium with an oversized protein skimmer is vital for maintaining high water quality.
- Flow
- Stagnant
- They originate from reef environments and appreciate strong, turbulent water flow. Excellent water movement aids in keeping the tank oxygenated and the fish physically active. Powerheads should be used to eliminate any dead spots in the aquarium.
- Reproduction
- Oviparous
- Breeding the Foxface in a home aquarium is considered impossible for the average aquarist. They are pelagic spawners that release their gametes into the open water column. The larval stage requires microscopic planktonic foods and very stable, large-scale systems to survive.
- Compatibility & tankmates
- They are a superb community fish that gets along with almost any tank mate, from small wrasses to large tangs. Because of their venomous spines, even highly aggressive fish will generally leave them alone. While considered reef-safe, they might occasionally nibble on soft corals if their diet lacks sufficient algae.
- Tank level
- Middle/Bottom
- They are extremely active swimmers that will constantly patrol the middle and upper levels of the tank. They require a large, open swimming area to stretch their fins and prevent stress. They also need large caves in the rockwork to retreat into when resting or frightened.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 2.7 ± 0.3 se
- Resilience
- High (less than 15 months)
- Phylogenetic uniqueness (PD50)
- 0.5
- Bayesian Length-Weight
- a = 0.01318, b = 3.06
- VulnerabilityLow vulnerability (21 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
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