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Obsidian Tang – Acanthurus gahhm

Overview:
The Obsidian Tang is a striking marine herbivore, known for its deep black to dark gray body with subtle blue highlights and a contrasting vibrant yellow tail. Its bold coloration and active swimming make it a standout in large reef aquariums.

Origin:
Native to the Indo-Pacific, primarily found along coral reefs and lagoons in Red Sea, East Africa, and the western Indian Ocean.

Feeding:
Primarily herbivorous – thrives on marine algae, seaweed, and spirulina-based foods, supplemented occasionally with meaty foods like mysis shrimp for balanced nutrition. Regular feeding helps maintain coloration and digestive health.

Tank Mates:
Best kept with peaceful to semi-aggressive tank mates. Avoid housing with overly aggressive tangs to minimize territorial disputes.

Aggression:
Moderately territorial – may defend feeding areas, especially in smaller aquariums, but generally compatible with other robust fish.

Experience Level:
Intermediate to advanced aquarists – requires a mature aquarium with ample swimming space, stable water conditions, and a proper herbivore diet.

Water Parameters:

• Temperature: 74–80°F (23–27°C)

• pH: 8.1–8.4

• Salinity: 1.020–1.025

• Minimum Tank Size: 125+ gallons

The Obsidian Tang is a visually striking, active herbivore, perfect for reef or large community marine tanks where a bold, dynamic fish is desired.

Above images for illustration purposes only. Exact colours, patterns, and size may vary between individuals.

Please note: The livestock that is sold on our online site is not held in store at our Swell shop, or available for collection from the shop. Species sold at our Swell store will differ from ones available to order to your door.

All livestock deliveries are subject to our full Delivery Terms & Conditions, please read before ordering.