Tangs · Acanthuridae
Care levelIntermediate
Blue-spotted Bristletooth Tang
Ctenochaetus marginatus
Fine blue spots cover a dark body, with delicate blue markings on the fins. This larger bristletooth needs established browsing surfaces, dependable supplemental feeding and enough space to settle.
Grows larger than some familiar bristletooths. Space, productive browsing surfaces and competition for food need careful planning.
Recommendation
Would you recommend this fish for a suitable saltwater aquarium?
180+ galRecommended tank
10.5 inchesAdult size
Semi-aggressive / territorialTemperament
Generally compatibleCoral safety
+ Why you’ll love them
- Fine blue spots cover a dark body, with delicate blue markings on the fins.
- Browses algal films on established surfaces.
- Generally compatible with corals when appropriately housed.
! Things to consider
- Needs adult-sized housing: plan for 180 US gallons or more with suitable swimming space.
- Grows larger than some familiar bristletooths. Space, productive browsing surfaces and competition for food need careful planning.
- Requires a consistent feeding routine and stable water.
- Has sharp tail spines; handle carefully.
Tank and habitat
- Recommended volume
- 180 US gallons or larger; allow for stocking and layout.
- Full-grown size
- 10.5 inches (maximum adult size)
- Tank footprint and swimming space
- Choose a long rectangular aquarium with open swimming lanes and room to turn. Leave space around rockwork; a tall narrow tank is a poor substitute for swimming length.
- Tank maturity
-
6 months recommended
Use an established, fully cycled aquarium with stable filtration and productive grazing surfaces. Confirm water stability and reliable feeding access before introduction. Suggested tank age is a planning guide, not proof of readiness. Complete cycling, stable water and the right food supply are essential. - Habitat and equipment
- Provide good circulation and gas exchange. Arrange secure rockwork for shelter and grazing, keep open water available, and use a secure lid. Take care around the sharp tail spines.
Care and compatibility
- Temperament
- Semi-aggressive / territorial
- Why this care level
- Grows larger than some familiar bristletooths. Space, productive browsing surfaces and competition for food need careful planning.
- Suitable tank mates and conflicts
- Choose tank mates that allow uninterrupted browsing and feeding. Other bristletooth tangs and established territorial surgeonfish can cause persistent disputes.
- Alone, pair or group
- A single tang is the simpler plan. Keeping several requires additional space, individual assessment and a way to separate incompatible fish; wild groups do not establish an aquarium stocking rule.
Corals and invertebrates
- Coral safety
-
Generally compatible
Generally compatible with corals, but observe the individual. Algae grazing should not be mistaken for a guarantee that no picking will occur. - Shrimp safety
-
Generally compatible
Generally compatible with ornamental shrimp; monitor introductions and individual behavior. - Snail safety
-
Generally compatible
Generally compatible with snails. Continue observing grazing behavior around small invertebrates. - Clam safety
-
With caution
Use caution around clam mantles: surface browsing can lead to unwanted picking. Observe closely and separate if persistent irritation occurs.
Food and feeding
- Diet
- Herbivore / surface browser; algal films and prepared foods
- Feeding plan
- Provide mature films and fine grazing material on rockwork, supplemented with suitable algae-rich preparations. Offer food consistently and check body condition; natural grazing is a supplement, not a complete feeding plan.
- Prepared or live food
- Try small herbivore pellets, spirulina-rich preparations, marine algae and suitable frozen foods. Ask what the individual already eats; acceptance varies.
Water conditions
- Temperature
- 72–78 °F (22–26 °C) is a commonly published aquarium reference range. Maintain stable conditions and consider the needs of the whole community.
- Specific gravity
- Specific gravity 1.020–1.025 appears in common species-care guidance. Match the needs of corals and other inhabitants, and avoid abrupt changes.
- pH
- pH 8.1–8.4 is the published marine aquarium reference range used here; maintain stability rather than chasing a single reading.
Long-term care
- Lifespan
- The linked references do not establish a reliable typical captive lifespan for this profile. Plan for long-term care and maintain a realistic adult housing commitment.
- Growth and future planning
- Adults may reach about 10.5 inches. Growth depends on the individual and conditions; juvenile purchase size should not determine the long-term aquarium.
Before you buy
- Is this fish right for your tank?
- Confirm Ctenochaetus marginatus and observe both browsing and acceptance of offered foods.
- Buying checklist
- Ask to see the fish eat. Look for a well-filled body, clear eyes, intact fins and normal swimming and breathing. Plan quarantine and confirm the seller’s species identification and feeding routine.
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