The hit animated children ’s movie ‘Finding Nemo’ has made the already popular Blue Tang one of the most popular saltwater aquarium fish around. In the movie, one of the main characters is a colourful, playful and forgetful Blue Tang named Dory. Since the release of this movie it seems every child wants their own saltwater aquarium with their own Dory and Nemo and every set of parents is faced with the decision of whether to let them have it. This movies has had a massive impact on the aquarium hobby because for the first time in the eyes of the general public fish are seen to have a personally.

So what are Dory and her other Tang friends really like?

A Tang is an oval shaped fish which is flat if viewed from front on. Tangs have a small single spine on each side of their caudal peduncle (just before their tail) that can be extended if required for self defence. Where a Tang has one or more larger spines which are not retractable in the same position, it belongs to the Surgeon family. When these fish fight, they will rapidly slap their tail towards their opponent trying to slash them with their spine.

The name Tangs or Surgeonfish is a common name given to many of these closely related fish species. It is commonly accepted that all Zebrasoma species are to be called Tang and all species with 2 spines are to be call Surgeonfish, while all the other single spined species seem to be called Tang or Surgeon depending on who you talk to e.g Blue Tang / Blue Surgeonfish.

In an aquarium Tangs are generally a very greedy fish, accepting a wide variety of foods ranging from flakes, pellets and seaweed to brine shrimp and more. These fish are often found grazing on rocks so one of their major benefits is controlling algae in an aquarium. As they will feed off algae from the rocks they are able to graze most of the day, so most species don’t need to be fed every day but some active species such as the Lipstick Surgeon which don’t graze as much, do need to be fed more often. Because these fish are so active it is important to ensure that they don’t lose condition due to under feeding which is common in many reef aquariums.

Tangs can be quite aggressive, mainly to their own kind or to similar shaped fish. As they are territorial, it is important to try to add any Tangs to your aquarium on the same day if possible. This way they have an equal chance of establishing territories. If you have to add a Tang to a tank that has established Tangs in it already, then it is a good idea to rearrange the rocks in order to disorientate the established fish. It is also safer to add more then one Tang at a time to divert the attention of any would be aggressors. These fish often don’t do well if kept in pairs as one will regularly dominate the other one they are best kept singularly or in groups. When one Tang is introduced to another it will usually take about three days for them to sort out their dominance hierarchy before they will get along. The more size, shape and colour difference the quicker this will tend to be. There is always a risk when adding a Tang to an aquarium with other Tangs as they may prove incompatible and might even kill each other.

Tangs are very prone to white spot disease as they have skin and not scales. It is a good idea to quarantine these fish using medications like copper sulfate or formalin for a period of around 2-3 weeks before they are introduced to a display tank to reduce the chase of them spreading disease to other fish in your tank.

It ’s highly recommended to only introduce Tangs to a tank with a salinity level as low as 1.018. This low level eases osmotic stress and will reduce the risk of white spot infection. If you have a display aquarium, it is harmless to the corals to drop the salinity over a period of about a week and raise it slowly again over the next week once the fish have been introduced safely. The corals may not open up as well while the salt level is low but will return to their former glory once the salinity has been slowly returned.

Any time these fish do contract white spot, drop the salinity and ensure you feed food high in garlic. Most good aquarium shops will stock food high in garlic such as New Life Spectrum flakes or Seachem ’s Garlic Guard solutions which can be added to other foods in order to reduce the susceptibility of a fish are to parasitic infections such as white spot.

Head and lateral line erosion is another common condition with Tangs, which tends to be a problem with fish that have been kept for many years on a low vitamin diet. Fish affected by this condition will have what appears to be small craters on its head or along its lateral line. Increasing the quality and variety of food offered and specifically targeting the amount of vitamin A in the diet can see this condition reverse. It is important to do a complete review of water quality and to monitor what the fish is being fed if over time you see the condition or colour of the fish deteriorate. Just because a fish is feeding well in the short term doesn’t mean it is getting what it needs in the long term. You should always monitor the condition of the fish over time and remember that there is no substitute for high quality foods.

Tangs can grow very quickly in an aquarium so it is important to allow adequate room and plenty of hiding places as adults range from 15-40cm. Tangs will spend a lot of their day foraging among the rocks and will very energetically dart around the aquarium and especially in and out of the rocks. A good cover of rocks is important to these fish to ensure they have a dark place they can escape into to feel safe if they are stressed. Having a dark safe place will allow a fish that is stressed to calm down faster thereby helping it to maintain its immune system and prevent it from developing diseases.

Some of the most popular Tangs are the Blue Tang, Powder Blue Tang, Sailfin Tang, Yellow Tang, Purple Tang, Brown Scopas Tang, Achilles Tang, Kole Tang, Lipstick Surgeon and Orange Shoulder Tang.

The Blue Tang Paracanthurus hepatus is also known as a Regal Tang and is a common salt water fish found on coral reefs often in large schools feeding on algae or zooplankton. The Blue Tang is without a doubt the most popular species of Tang, its bold colour and boisterously active nature making it a temptation for every hobbyist. This fish is very widely available, and is found on many reefs in the world, most commonly Australian. It is gluttonous, fast growing and it can get to about 30cm long.

This fish is well know for it choice of sleeping arrangements as it will often tuck into some of the most bazaar and uncomfortable looking positions when it retreats for the night, often at the same time each day regardless of whether the light is on or off. Another behavior common to this fish is a habit of lying on the bottom of the tank like it is dead. This is often pointed out to me by children while I am working in an aquarium retail store. The children will often say Excuse me Sir, the fish over there is dead and sure enough every second time it is just a Blue Tang practicing it ’s strange resting habit. With a small tap on the glass, the children are happy to see the fish jump up hoping to get a feed.

Careful consideration must be given before adding this fish as it gets white spot very easily and therefore quarantining is highly recommended. A Blue Tang should only be introduced to a tank with a low salt level.

Once this fish has settled into the tank it can become a very hardy, long living fish that will bring you and the family years of enjoyment.

The Powder Blue Tang Acanthurus leucosternon is a fish rarely recommended as it is similar to the Blue Tang but its success rate in an aquarium is even lower. In many aspects, it is similar to keep to a Blue Tang but is more susceptible to white spot and will die very easily, partly because it is not found in Australia and is therefore imported, meaning that it is probably quite stressed by the time it even reaches an aquarium store. It is important that you only buy fish from a retailer that you are confident in and only deals in net caught fish as this fish comes from the Indo-Pacific where catching fish using cyanide is common.

A big warning to everyone wanting to get this fish is that once settled it can become very aggressive. Although it will not grow as fast as a Blue Tang it can reach up to 25cm.

The Achilles Tang Acanthurus achillies is one of the most sought after and asked about Tangs. Many people will enthusiastically request this fish until they find out how hard it is to get, how expensive it is and how hard it is to keep. In many aspects such as size and survival rate this fish is quite similar to the Powder Blue Tang only bigger, less aggressive and even harder to keep.

Its rarity coupled with its low survival rate and very high price means it is recommended only if a high quality and over sized UV sterilizer is run on any display tank housing this fish. The money saved not having to replace this fish after several attempts to keep it may pay for even the best of UV units, which will benefit your entire tank ’s inhabitants.

The Sailfin Tang Zebrasoma veliferum is a true Tang and a great choice as an aquarium fish as it has great colours, is easy to keep and is not too expensive because it is easily available in Australia.

This fish can reach 40cm in length so it should be allowed adequate room to grow. As with all fish their growth will be stunted if kept in a small tank.

This fish is very similar to the more expensive and rarer Red Sea Sailfin Tang Zebrasoma desjardinii which is also a great fish to keep in an aquarium. The Red Sea version has darker stronger pattern but is not as common or as robust when first introduced.

It is rare to see a reef aquarium without a Yellow Tang Zebrasoma flavescens; this is because it is such a wonderful aquarium fish which loves to eat algae. Its striking yellow colour is unmistakable, along with its boisterous; gluttonous personality it is a must for every reef aquarium. You may recognise the Yellow Tang as Bubbles in the movie Finding Nemo, and its inclusion as a character has also seen the popularity of this Tang increase with the general public. It is common to have children in an aquarium store standing in front of a tank containing a Yellow Tang calling out to their parents Look, look its Bubbles.

Yellow Tangs most commonly come from Hawaii and can grow to 18 cm in length but normally much slower than other species of Tang. The colour of this fish can become quite patchy at night but it is bright yellow during the day.

This fish tends to be very easy to keep and I often find it my first choice when recommending a Tang for any aquarium.

The Brown Scopas Tang Zebrasoma scopas is rarely expensive and is very good to keep as it is very hardy and has all the same behaviours of the Yellow Tang but is a little more shy. This fish is commonly available in Australia but not so commonly sold because as the name suggests, it is not bold in colour, so it is not a prized fish in the hobby. This fish is very good for beginners and has lovely blue marking if you look up very close to the fish.

The Purple Tang Zebrasoma xanthurus is from the Red Sea is very similar to the Yellow Tang but much more expensive, rare and aggressive. Most aquarium stores are lucky to get these fish a couple of times a year and the stock sells very quickly as they are easy to keep and a real novelty to many patient aquarist.

If you wish to keep a Yellow Tang with a Purple Tang it is worth ensuring that the Yellow Tang is much larger than the Purple as the Purple will tend to be more aggressive. Although these fish are commonly kept together it does not always work as they are aggressive to any other fish that is a similar shape to them. Housing more then one of these fish per tank is not recommended.

This fish is very susceptible to head and lateral line erosion, so it is very important to offer it a high quality varied diet from the start. Though they are mostly safely kept in reef tanks, this fish does tend to be rougher on the corals than most Tangs. They will normally only bother a few large polyp species.

Not quite as rare is the subtle but beautiful Kole Tang Ctenochaetus strigosus also called the Yellow Eyed Bristle tooth. This fish is found all over the world, grows to 15cm in length and though rarely appreciated by beginners, is very popular with the intermediate hobbyist that is prepared to pay a bit more for a lovely fish. This fish is a great addition to most tanks as it rarely causes any trouble, eats lots of hair algae, gets along with most fish and is not too hard to keep.

This fish is a great catch any time it is available. You will rarely ever hear a bad word about them from anyone.

A large male Lipstick Surgeon Naso lituratus can get to 50cm and has long parallel whips on the top and bottom of its tail making it a very striking sight. This fish is very reef safe and will do best in a large aquarium; they even do well as a pair as they is rarely aggressive. This fish is often hard to keep in the long term because even when this fish does seem to be feeding, it may still die of starvation over time. It is a large, active fish that often consumes low nutrient foods so nutrition is the biggest concern for this fish. When this fish is stressed it will often swim erratically and not feed. This drain of energy is a very common cause of death with this species. Products like Stresscoat which contain Aloe Vera do tend to have a calming effect on these types of high stress fish. Any fish that swim erratically instead of hiding when they are stressed are always at a disadvantage in an aquarium. In order to maintain this fish for an extended period of time you need to ensure it is receiving adequate high quality foods, and feeding at least twice a day. There is a slightly more expensive Blonde version from Hawaii which has a yellow stripe on the top of the fish in place of the normal black one.

I will rarely recommend this fish, although it is a very good selling fish because of its charm. I do suggest that you make sure that the fish is feeding before you purchase it.

Finally, the Orange Shoulder Tang Acanthurus olivaceus is a very large, common, easy to keep, trouble free Tang from Australia and perfect for any aquarium. When this fish is small it exhibits a beautiful orange colour but as it grows it takes on more of a dull greenish colour with an orange shoulder. Despite their fading colour, these fish still sell quite well because they are normally reasonable priced when sold in Australia

There are many fish in the Tang and Surgeon family that are worth considering as additions to you tank. Size, hardiness, aggression, rarity and price are all factors which need to be taken into account in your decision making.

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Understanding the effect of the system in marine environments is the key to mastering fish keeping.
One of the leased talked about issues in marine aquarium keeping is the need to facilitate the functioning of a fish’s osmoregulation system. The osmoregulation system is responsible for maintaining a healthy balance of fluids and salts within the fish itself.

The higher the amount of salt in the water the harder the osmoregulation system has to work to maintain correct levels of salt and other minerals within the fish, so the higher the osmotic pressure.
The salt levels a fish can tolerate will depend on the environment from which the fish has evolved. Freshwater fish can only handle very low osmotic pressure compared to saltwater fish which are used to withstanding a higher level. Some fish are able to tolerate huge changes in salt level and osmotic pressure allowing them to travel from the salt water oceans, up the waters of freshwater rivers. Fish that commonly live in both fresh and salt water are known as brackish water fish.

There are also many salt water fish that will venture into fresh water at specific points in their lives. Many marine fish such as Salmon will travel right up fast following freshwater rivers to breed allowing their young to grow up in safer stream nurseries away from the threats lurking in the oceans. Once the offspring are large enough they will return to the sea where there is adequate food for them to grow and thrive.

A fresh water fish generally maintains its internal salt level higher than that of the surrounding water. Its gills take in salt from the environment along with oxygen. A large amount of water is constantly diffused into a fresh water fish and excreted as urine so that its system is constantly being flushed. On the other hand, a marine fish has an internal salt level lower than the surrounding water so the osmotic pressure naturally pulls water out of the fish and pushes salt in. Consequently, to maintain the correct salt level, a salt water fish needs to actively excrete salt out of its gills.

A marine fish in water with a slightly higher salt level will devote more molecular energy to osmoregulation; therefore if the fish is suffering from stress lowering the salt level will help the fish to recover. Lowering the salt level will reduce osmotic pressure within the fish allowing it to allocate more of its molecular energy to its immune system, This will help stop the stressed fish from becoming sick and can be used to treat fish that are sick.

The ocean is the most stable ecosystem in the world occupying 77% of the earth’s surface area and experiences very little seasonal fluctuations in salt levels in comparison to tiny freshwater lakes and rivers. Most marine fish can only handle about 2 degrees of salt change per day e.g. 1.023 to 1.025. Understating the osmoregulation system can help protect your display aquarium. Every fish you introduce will be initially stressed and it will usually take about 3 weeks for the fish to settle in to a new environment and for its stress levels to return to healthy levels. During this time it’s advisable to lower the salt level of your water to about 1.018, to decrease the osmotic pressure experienced by the fish and then gradually increasing it to your previous level (remembering of course to never lower or raise salt levels by more than 0.002 per day). This means that you need to start preparing your tank a few days before you introduce a new fish so that the salt level is right when you bring the fish home Once the fish appear to be doing well for a week you can slowly return the salt level to 1.025 and any time the fish appear stressed again it is worth reducing it to 1.018 again. Many of the corals will not enjoy the lower salt level and may not open up as well during this, but this will not lead to any long term problems.

Another reason to lower your salt level before introducing new fish is that although the ocean is commonly at a salt level of 1.025, and a perfectly run reef aquarium should match this, most aquarium retailers and wholesalers run their aquariums at a salt level of 1.018. This is to allow lower osmotic pressure which in turn reduces the prevalence of diseases among their fish. Because of this most reef tank are actually kept at 1.023 and fish only tanks at 1.020.

A different way to allow fish to gradually adapt to higher salt levels is to use a quarantine tank which can house the fish for 2-4 weeks before it is introduced in the main display tank. This means that the main tank can remain at the desired salt level while also allowing the fish to settle in and de-stress before it is introduced into the display tank. Another advantage of using a quarantine tank is that it reduces the levels of pathogen in your display tank. When fish are stressed, for example when they are being brought home from an aquarium retailer, they release peaks levels of pathogens into the water. These pathogens are not only dangerous to the new fish, but can also make your existing fish sick. If you have a quarantine tank, you can medicate the fish separately and reduce the threat of disease in your new and old fish.

Once the new fish is ready to be introduced into the main tank, you should slowly adjust the salt and pH levels and also the temperature to that of the display tank. This way, you don’t have to acclimatize the fish in your display tank but rather easily transfer it across in a net. This quick and simple move from the quarantine tank to the display tank will be stress free compared to what the fish has had to go through to get to you.
Given all the advantages, it is very advisable to use a quarantine tank. However, if the quarantine tank is too small or you cannot provide the correct conditions, then the fish are better off being introduced straight into the main tank.

All the techniques mentioned above can be used whenever any of your fish are sick or stressed, not only at the time they are introduced. You can at any time place a stressed or a sick fish in a quarantine tank with a lower salt level compared with that of your display. Another approach is to perform a freshwater dip on any sick fish or coral. To do this, place the sick marine animal in freshwater with the same temperature and pH as your tank for 10 minutes. This allows the osmotic pressure to kill any pathogens and bacteria that maybe affecting your animal but usually not killing it. In most cases, if the animal does not survive the freshwater dip it was probably not strong enough to survive anyway. The dip can be repeated daily if necessary.

So next time your fish are experiencing stress or illness, help boost their immune system by relieving osmotic pressure.

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