Achilles Tang accepts primarily plant-based material as food. In fact, just like its cousins in the same fish family such as the chevon, powder blue and yellow tang, their main source of diet is usually algae growing on the surface of live rocks. You can even consider varying their diet with use of dried seaweed wafers or spirulina, which can be easily bought at certain aquarium stores. Based on my experience and collected info, what I find is that with wide range of different foods, the fish stands better chance to survive in captivity and live longer. Unfortunately on both occasions that I have with my own achilles tang, the first one managed to survive for only 3 months while the second one live longer close to 2 years.
When it comes to fish compatibility, surgeonfish can be very territorial when housed together with their own kind but with other fish species such as clownfish, blennies and other invertebrates, generally they will tolerate their presence with minimal aggression. This proves to be no exception with achilles tang and in fact, with their bright orange colored tail, it’s a sign and warning to other invading fish species that they will attack when being threatened. Generally, the fish is often seen living in pairs only during mating season while the rest of the time, achilles tang is often seen swimming alone especially during the juvenile period. Therefore, the fish is best kept with only one of its kind in a single saltwater tank.
Related to water quality, Acanthurus achilles is very particular about changes in testing parameters such as ammonia and nitrite content including water salinity level. So far based on my observation, they generally do well in sg range between 1.022 to 1.026 measured using hydrometer and it’s best to avoid any fluctuation especially during aquarium saltwater change. For pH, anywhere around 8.0 to 8.5 should be alright and still within their tolerance limit. Apart from that, Achilles tang is also susceptible to aquarium fish disease such as parasites and ich infestation and therefore, water quality is always your main focal point here. Finally, a good marine hobbyist is always well prepared and as such, basic supplies like aquarium medication, pH test kit should always be around for use during emergency.
Other types of tang fish: Pacific Sailfin & Yellowtail Purple Tang