Tangs or Surgeonfish have become a mainstay of the aquarium hobby due to their attractive colouration, long lifespans and wide distribution in the world’s oceans.
Tangs in the Wild
In the wild, tangs roam across large areas of coral reefs and are constantly on the move, grazing on marine algae as they go. Tangs are found in shallow reef waters, as this is where marine algae are most abundant. These areas are exposed to a great deal of water movement caused by surface currents and waves. Aquarists should replicate this water movement and provide as much swimming room as possible to replicate natural conditions.
Getting the Tank Right
Tangs are very mobile fish, therefore, a large aquarium is absolutely essential. Not only does a large tank provide enough swimming space, it helps diffuse aggression between individuals. For this reason, tangs should never be kept in aquariums under 380 litres (100 gallons). Most tangs will not do well when kept together, however, some of the smaller species like yellow tangs (Z. flavescens), can be kept in groups but only in large tanks of 1200 litres (300 gallons) or more, and even then only when all of them are roughly the same size and added to the tank at the same time.
Species Selection and Tank Mates
Aquariums over 380 litres (100 gallons) can accommodate Powder Blue (Acanthurus leucosternon), Pacific Blue (P. hepatus), and Purple tangs (Z. xanthurum) with ease. With an increase in tank size, sailfins (Z. veliferum and Z. desjardinii) can also be kept. Other species, such as the orange shoulder tang (A. olivaceus), the lieutenant tang (A. tennentii), Naso (Naso lituratus) or Sohal (A. sohal) tang can be quite a handful and will assert their dominance in an aquarium. Therefore, a larger aquarium is required for those species with 1500 litres (400 gallons) being ideal.
As with any potentially aggressive marine fish, tangs should be added to the aquarium last. If added first, tangs will establish a large territory and bully every other fish added from then on. Adding them last will prevent this. Aggression also varies between individuals, with some being more aggressive than others. It is therefore a good idea to treat every tang as an individual and take each situation on a case-by-case basis.
Aggression is often directed towards similarly shaped or sized fish, such as Angelfish or Butterflyfish. Therefore, adding these fish to an aquarium with an adult tang in residence can be problematic. There are however ways of limiting aggression. Changing the aqua-scape before adding new fish can disrupt the territorial behaviour of aggressive fish and provide time for newcomers to acclimatise to new surroundings. Placing a divider in your tank to allow newcomers to establish themselves can also work.
Water Quality and Movement
Large amounts of water movement will replicate a tang’s natural environment and help maintain water quality, when used in combination with efficient filtration. With their habit of eating continuously throughout the day, tangs need a tank with a powerful filtration system. Here, it would be a wise idea to purchase a skimmer designed for a larger system to ensure that there is sufficient filtration.
Both chemical filtration and a refugium play a significant role in the aquarium. These are especially important with tangs which produce significant amounts of nitrates and phosphates. If you’re keeping a collection of corals, which can suffer at detectable phosphate levels, these become increasingly important.
While algae form the bulk of a tangs diet in the wild, tangs in captivity will take meaty foods such as mysis and brine shrimp. Their staple diet should consist mainly of marine algae and even occasional treats from the refugium. Many sources in hobbyist literature suggest that terrestrial greens, such as spinach and lettuce, are too low in protein and vitamin content to be of any value. Dried algae sheets specifically prepared for fish can be soaked in or treated with supplements to increase their nutritional content. Tangs also enjoy flaked foods, especially those rich in algae.
Sadly, tangs are prone to disease and will often be the first fish in a tank to show signs of infection, often as a result of stress brought on by poor water quality. As always, five minutes of planning saves five hours of frustration, so ensure that you remain on top of your maintenance schedule and the tangs will reward you with many years of life. Diet is also important, as a well-fed fish is better able to resist disease.
The best way to protect your fish is to use a quarantine tank to ensure that new purchases are free of infection and parasites. You should also ask your fish dealer if the specimens you’re planning to buy have been treated to kill any intestinal parasites. But again, to be safe, always quarantine your new acquisitions before adding them to the main tank to ensure that they are feeding and healthy.