The Achilles Tang is found on various reefs of Oceania, up to the islands of Hawaii and Pitcairn. The fish is also, although less commonly, found in the Mariana Islands and even some reefs in southern Mexico and Guatemala. They are black with striking orange and white lining along their fins and tail. When this tang matures, a prominent orange drop shape develops on the caudal area, terminating into a sharp spine. They will use their spines as a weapon against other fish that threaten them. The juveniles of this species have an orange marking by the tail in the shape of a streak instead of being teardrop in shape. The Achilles Tang can reach up to 10 inches in length and requires an aquarium of at least 100 gallons with live rock and plenty of room to swim.
Tangs, in general, are primarily herbivores. They need rocks to graze on as their diet is primarily marine algae. For tanks on the smaller side that have less live rock to grow algae, you will need to supplement your tang’s diet with Nori or other vegetable matter like Nori, Romaine lettuce, spinach leaves, or broccoli. They also will accept flake foods and sometimes small meaty offerings like Mysis shrimp. A good variety of foods will keep your tang healthy and vibrant. A well-fed tang won’t pick at your corals, but there is always a possibility if there is no algae or Nori present. Also, a well-fed Tang has less chance of developing HLLE (Head and Lateral Line Erosion). HLLE can be fatal depending on severity and can leave lasting scars on the tang
As stated earlier, an Achilles Tang can reach up to 10 inches and requires an aquarium of at least 125 gallons with live rock and plenty of room to swim. Tangs, in general, will spend their days swimming from one side of the aquarium to the other, picking on any algae growing on your live rock or frag plugs. In the ocean, tangs swim great distances every day. This should give you an idea of how much swimming space a tang will need to be satisfied in your tank. It is also recommended that your tank be wider than it is tall, to allow them more space to swim. Without ample space to swim, a tang can become stressed and will be very prone to diseases like Ich.
Achilles Tangs can be very aggressive to other tangs, but are usually peaceful with other non-Tang species after they establish their place in the pecking order of the tank. With the spines built into their tails, they are usually at the top of that pecking order. Keeping your Achilles Tang well-fed will reduce aggression in your reef. If you intend to keep fish, a netted lid is recommended.