Black Spot Foxface - Siganus unimaculatus

Black Spot Foxface (Siganus unimaculatus)

The Black Spot Foxface, Siganus unimaculatus, is a striking and useful marine rabbitfish, recognised for its bright yellow body, bold black-and-white facial markings and distinctive black spot on the upper rear body. Also known as the One Spot Foxface or Blotched Foxface, this species is popular in mature marine aquariums for its algae-grazing behaviour, peaceful temperament and eye-catching colour. It is generally hardy once settled and can be an excellent functional fish for larger reef or fish-only systems, but it should be treated as reef safe with caution due to possible nipping at some corals and sessile invertebrates.

Common Name:
Black Spot Foxface, One Spot Foxface, One-Spot Foxface, Blotched Foxface, Blackblotch Foxface, Foxface Rabbitfish, One Spot Rabbitfish.

Scientific Name (Latin):
Siganus unimaculatus

Maximum Size:
Up to around 20 cm, making it a medium-sized rabbitfish that requires good swimming space and long-term planning.

Water Type:
Marine

Origin / Natural Habitat:
Found across the central Indo-Pacific and Western Pacific reef regions, including areas around the Philippines, Indonesia, northern Australia and nearby island reef systems. In the wild, Black Spot Foxface inhabit rich coral areas of lagoons and outer reefs, often around staghorn corals and algae-covered reef structure. Juveniles may occur in larger groups, while larger juveniles and adults are more commonly seen in pairs.

Water Parameters:
Temperature: 24–27°C
pH Range: 8.1–8.4
Hardness or Salinity: SG 1.020–1.025

Temperament:
Peaceful to semi-aggressive. Black Spot Foxface are generally calmer than many tangs and can be kept with a wide range of peaceful to moderately robust marine fish. They may become territorial towards other rabbitfish, foxfaces or similarly shaped algae grazers, especially in smaller aquariums. Usually best kept singly unless a confirmed pair is available and the aquarium is large enough.

Diet:
Primarily herbivorous grazer. In the wild, this species feeds heavily on seaweeds and algae. In the aquarium, offer frequent feeds of marine algae sheets, nori, spirulina flakes, herbivore pellets, algae-based frozen foods and quality marine grazing foods. Small amounts of frozen mysis shrimp, enriched brineshrimp and finely chopped marine foods can also be offered, but the diet should remain strongly algae-focused. Regular feeding helps maintain colour, body condition and can reduce the chance of coral or invertebrate picking.

Minimum Tank Size:
A practical minimum of around 400–500 litres is recommended for a single specimen, with larger aquariums preferred for long-term adult care. Provide open swimming space, mature rockwork, strong filtration and natural grazing surfaces.

Behaviour & Activity:
An active daytime grazer that spends much of its time cruising around rockwork and picking at algae films or seaweed growth. It may be shy when first introduced and can display stress colouration or camouflage patterning when frightened, resting or sleeping. Once settled, it often becomes bold, visible and highly useful as part of an algae-management approach. A secure lid is recommended, as startled marine fish can jump.

Reef Safe:
Reef Safe with Caution
Black Spot Foxface are often kept successfully in reef aquariums and do not usually damage corals when well fed. However, individual behaviour can vary, and some specimens may nip soft corals, fleshy LPS corals, zoanthids, clam mantles or other sessile invertebrates. They are usually safer in mature reefs with regular algae-based feeding, but they should not be considered completely risk-free.

Special Requirements or Care Notes:
Black Spot Foxface have venomous dorsal, anal and pelvic fin spines, so they must be handled with care. They are not aggressive towards people, but accidental contact with the spines can be painful. Use containers rather than hand-catching where possible and take care during maintenance. Best kept in a mature aquarium with stable water quality, plenty of algae-based food and peaceful tank mates. Avoid mixing casually with other foxfaces or rabbitfish unless the aquarium is large and compatibility has been carefully considered.

Suitable for:
Intermediate fishkeepers

Availability:
Regularly available in the marine aquarium trade / Availability can vary depending on size, supplier and import season

All images are a visual representation of the fish you will receive, made to be as accurate as possible. Please note that Mother Nature is a wonderful thing, and variation in patterns and colours will occur — that is part of the unique beauty of these animals.