Foxface Rabbitfish
Siganus vulpinus
Also known as: Foxface, Common Foxface, Black-face Rabbitfish, Black-face Rabbitface, Foxface Lo, Badger Fish
Siganus vulpinus is that bright yellow "fox-masked" rabbitfish you see cruising around picking at algae all day. It's generally chill with other fish, but it can get a little bossy with similar-shaped grazers-and those dorsal spines are venomous, so nets and hands need to be treated with respect.
The Foxface Rabbitfish features a yellow body with distinctive black markings and long dorsal spines that resemble a fox's face.
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Quick Facts
Size
25 cm (about 9.8 inches)
Temperament
Semi-aggressive
Difficulty
Intermediate
Min Tank Size
125 gallons
Lifespan
8-12 years
Origin
Western Pacific (Indo-Pacific)
Diet
Herbivore/omnivore grazer - mainly algae/nori/spirulina foods, plus occasional meaty frozen foods
Water Parameters
23.8-31.2°C
8-8.4
8-12 dGH
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Calculate heater sizeCare Notes
- Give a foxface room to cruise-think 90g+ with lots of open swim space and a few rock caves to duck into when it gets spooked.
- Keep salinity steady around 1.025 and temp 75-79°F; they're hardy, but they sulk (and get spotty) when salinity swings or nitrates stay high.
- Feed like a herbivore that still likes snacks: nori on a clip most days, plus spirulina/marine algae foods; toss in mysis or brine occasionally but don't make it the main diet.
- They're great for nuisance algae, but they can also "taste test" some softies/LPS if they're hungry-keep them well-fed if you want your corals left alone.
- Tankmates: generally chill with other peaceful fish; avoid housing with super aggressive tangs/triggers that will harass it, and don't mix with other rabbitfish in smaller tanks unless it's a big system.
- Watch the dorsal spines-venomous and painful; use a container instead of a net when moving it, and don't corner it with your hand in the rockwork.
- If it suddenly turns blotchy/dark, that's usually stress camo (lights off, new tankmates, being chased); give it hiding spots and reduce bullying before you start dumping meds.
Compatibility
Good Tankmates
- Peaceful clownfish (Ocellaris/Percula) - they mostly mind their own business and the foxface just cruises around grazing.
- Fairy or flasher wrasses - active but not usually pushy, and they won't compete much with the foxface's 'constant grazer' vibe.
- Tangs that aren't total jerks (Kole/Yellow/Eye-bristle types in a big tank) - usually fine if there's room and plenty of nori/algae so nobody gets possessive.
- Peaceful gobies and blennies (watchman goby, tailspot blenny, etc.) - they stick to their zones and the foxface ignores them.
- Reef-safe-ish community fish like chromis or cardinals - good 'middle water' fish that don't mess with a foxface.
- Most dwarf angels (coral beauty/flame) in a roomy setup - usually works; just keep everyone well-fed so it doesn't turn into 'who owns the rockwork'.
Avoid
- Other rabbitfish/foxfaces - mixing is asking for turf wars unless the tank is huge and you add them together; otherwise they'll often scrap.
- Aggressive/nippy triggers (clown/picasso, etc.) - they'll pester the foxface and that stress tends to bring out the foxface's defensive spine drama.
- Pushy big wrasses and similar bullies (harlequin tusk, large Thalassoma types) - they can harass a foxface nonstop, especially at feeding time.
- Territorial dottybacks (especially in smaller tanks) - they love picking fights and can keep a foxface on edge around caves and rockwork.
1) Where they come from
Foxface rabbitfish (Siganus vulpinus) come from Indo-Pacific reefs and lagoons—places with bright light, lots of rock, and endless grazing opportunities. That “horse face” snout isn’t just cute; it’s made for picking algae and bits of planty stuff out of cracks all day.
2) Setting up their tank
Think “room to cruise + rock to graze.” A foxface is active and gets chunky fast. You can start one in a 75g if it’s a smaller fish, but long-term I’ve had the best luck (and least pacing) in 90g+ with open swimming lanes.
- Tank size: 75g minimum for a smaller one; 90–125g feels more natural as they grow
- Aquascape: rockwork with lots of surfaces for algae, plus open areas up front
- Flow/oxygen: moderate flow and good gas exchange—they’re constant movers
- Cover: they can spook and bolt; a lid or mesh top saves lives
- Hiding spot: one “cave” or overhang they can wedge into at night
If your foxface turns mottled or looks like it’s wearing camouflage at night, that’s normal. Mine always did the “pajamas” look when sleeping or stressed, then went bright yellow again after lights-on.
They have venomous dorsal spines. Not aggressive, but you don’t want to get tagged while netting or moving rock. Use a container to catch them when you can, and go slow.
3) What to feed them
They’re hungry herbivores/omnivores with a strong bias toward greens. If you feed only meaty frozen, they’ll survive… but you’ll be fighting a losing battle with weight, digestion, and “why is it nipping my corals?” behavior.
- Nori/seaweed sheets (daily if possible) clipped to the glass or on a feeding rock
- Spirulina flakes/pellets as a staple
- Frozen mixes with some veggie content (mysis is fine, just not as the main event)
- Blanched macroalgae if you have it (some will eat it, some ignore it)
- Occasional treats: chopped clam, brine, mysis—think “snack,” not “diet”
Give them a grazing routine: a nori sheet in the morning, then a smaller feeding later. Foxfaces calm down a lot once they learn food shows up reliably.
If they’re underfed on greens, they may sample soft corals or certain LPS. It’s not guaranteed, but hunger makes it way more likely.
4) Behavior and tankmates
Foxfaces are generally peaceful, a little shy at first, and then oddly personable once they settle in. Mine would follow me from end to end like a yellow puppy. They’re not usually bullies, but they’re big enough that timid fish can get intimidated just by the constant cruising.
- Good tankmates: tangs (usually), clownfish, wrasses, cardinals, gobies, dwarf angels (case-by-case), most reef-safe community fish
- Be careful with: very aggressive triggers, big mean dottybacks, or anything that likes to harass newcomers
- Other rabbitfish: possible in large tanks, but don’t assume it’ll be peaceful—introductions matter
- Inverts: typically fine with shrimp/snails; they’re not known invert hunters
They’ve got a neat defense trick: they can “lock” their dorsal spines. If a tankmate tries to take a bite, it gets a mouthful of bad decisions. That’s why they usually don’t need to be aggressive to hold their own.
5) Breeding tips (realistically)
Breeding foxfaces in home aquariums is pretty uncommon. In the wild they’re pelagic spawners (eggs and larvae drifting in the water column), which is a tough project without a serious larval setup. If you keep a pair and they get comfortable, you might see courtship behavior, but raising babies is a whole different hobby.
If you ever want to try, the biggest hurdles are: getting a true pair, providing a big stable system, and having live foods ready for tiny larvae (rotifers, then nauplii, etc.). Most folks focus on keeping them fat and happy instead.
6) Common problems to watch for
They’re pretty hardy once they’re eating, but the first couple weeks tell you everything. A foxface that won’t take greens or hides nonstop is usually stressed, getting bullied, or dealing with parasites.
- Marine ich/velvet: they can get hit like any other fish—watch for flashing, heavy breathing, and dusting/spots
- Refusing food: often shipping stress; offer nori first and keep the tank calm
- HLLE (head and lateral line erosion): more likely in systems with poor diet/low variety and lots of stray stress
- Coral nipping: usually a “not enough algae food” issue or a bored grazer in a too-clean tank
- Spine stings (you): not a fish health issue, but a common hobbyist problem
Don’t try to net them in a tight space unless you have to. Spines + net = stuck fish and a stressed-out mess. I use a clear specimen container and gently herd them in.
If you get stung: hot water (as hot as you can stand) helps with marine venom pain. Seek medical help if pain is severe, spreading, or you have any allergic-type symptoms. Not trying to scare you—just don’t tough it out if it’s bad.
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