Unicornfish as what the name suggests has a protruding horn-like feature that actually resembles the mystical creature that we all know about. It is special in its own way and although not all the unicorns have an extending horn, with exception a few species having a bulge instead on the forehead, nevertheless it is still easy trying to make out the difference when comparing them with the other fish. To correctly identify them probably takes a “getting used to it” approach and from there; it shouldn’t be difficult to spot one of these unique fish. The word Unicorn itself although might give the misleading impression that the fish is probably hardy and easy to take care of, but somehow, failure to really understand and focus on their specific needs can actually prove to be a costly mistake. Here, we shall discuss some of the basic things especially what a fishkeeper should know about them, and most important, the minimum requirements on how to keep them alive and thriving in your home aquarium.
What we know about the Unicornfish
Most people do not realize that Unicornfish actually share the same family grouping (called Acanthuridae) which also includes the Tang and Surgeonfish. It belongs to its own genus which is given a short and easy to remember name spelled as Naso. Although these fishes are all closely related to each other, somehow the other species like the Tang do not spot any of the protruding horn-like appearance just like what the Unicornfish does, but in and out they do share a few similarities in terms of overall body shape, general nutritional needs and water parameters. Like all the other Acanthuridae cousins, the Unicorns are also characterized by its thin and flat body shape and most notable that you should also noticed is its small-sized mouth opening. Most of them prefer algae as staple meal but when they don’t feel like eating, sometimes you can entice them to eat by offering a small serving of brine shrimps, seaweed or even flakes. Never underestimate their appetite because being an active fish, your Unicorns can gobbled up a lot of foods sometimes demanding that you feed at least 3 to 4 times a day. There are at least 15 known species of the Unicorn fish group but our discussion here will only narrow down to 3 different species which are the most commonly seen right now. While two of them have the distinctive horn, the other obviously lacks the feature which only has a slight bump appearing on the forehead.
The Naso family
Spotted Unicornfish (Naso brevirostris)
They are probably known as the “true” uniform family because in terms of having the horn-like appearance, they sure deserved to be declared clear winner as their horn extends farther and longer compared to any of the other unicorn species. In fact, the length is actually known to increase with age. Just like the Tang fish, one of the requirements which you will need to constantly monitor is how to maintain a certain minimum level of dissolved oxygen level in the water just to keep them active or else you will find them lying at the bottom gasping for air. For your information, dissolved oxygen in the water is measured by ppm (parts per million) level and, if you have a DO meter installed for your fish tank, the level should indicate at least minimum 5.5ppm. By ensuring that the water remains oxygen rich, you will find that your pet unicornfish will appear to be active and lively. This means that the aquarium setup should at least have the wave maker to complement the existing aeration unit (filter, air pump) that you have installed so that they can complement each other to help increase the dissolved oxygen level. The same principle applies to all the other remaining unicornfish species which we are going to discuss later on.
Spotted unicornfish can be found exist in different colors depending on the locality which they were caught. Those found among the reefs close to the Hawaiian island are mostly bluish gray while there are others which are less seen with the pale brown coloration. Spotted unicorns are very active fish and an adult specimen can attain length reaching almost 2 feet. For that huge size, nevertheless they would require a corresponding aquarium size which should at least measure and custom-made to be about 8 feet in length with 300 gallon capacity to allow them enough space to swim around. The tank setup preferably needs to have an established ecosystem of reefs so that it will provide grazing spot for them to look for algae plus not to forget plenty of hiding space by cleverly arranging live rock for them to seek shelter away from constant distraction. Usually success in keeping them alive in home aquarium has been reported for juvenile fish but as they grow bigger, more problems will arise mainly on how to sustain their feeding frenzy. While mortality rate is low, further understanding and research about the fish acquired through years of experience has allowed aquarist to successfully keep them alive in aquariums. As far as captive breeding is concerned, there has not been much success but to remain positive, maybe somehow the scenario could change someday.
Blue-Spine Unicornfish (Naso unicornis)
Another fine example of a true unicornfish breed. Overall the coloration appears to be grayish accompanied by presence of blue green patches appearing on the fin and caudle peduncle. In the wild, blue-spines are mostly found in areas where the current is strong and particularly in areas where you can find huge cache of brown algae. Their presence is not only confined within the areas close to the reef but also in open waters where algae growth is abundance. In home aquariums, the fish preferably should be housed with the same condition similar as what we have described earlier so that this will allow them more room to acclimatize and adjust to the new environment. The biggest threat to their survival is probably due to depletion of natural foods which no matter how big the reef population can be, eventually there will not be enough algae growth to sustain their feeding habit. Thus if you can find another food source to complement their needs, that would certainly help. Blue-spine unicorns are generally considered reef-safe but just to be on the safe side, you have to make sure that they are well-fed in order to discourage them to forage in search of foods and ended up disrupting the ecosystem which eventually led to the destruction of the reefs. In terms of compatibility, both the blue spine and spotted unicornfish can be kept together with the other non-aggressive marine fish like community wrasses, royal gramma, centropyge angelfish and tolerate presence of small invertebrates like cleaner shrimps but care has to be taken if you intend to mix them with their own similar kind.
Orange-Spine unicornfish (Naso lituratus)
Also affectionately referred to as Naso tang, the fish seems to be lacking the usual unicorn horn. However, compared to both the spotted and blue-spine, the lituratus is considered more colorful and attractive. The pattern on its body formed by stripes of yellow and orange band running parallel on the underside, combined with the darker background that define the base coloration, all these sure help to make the fish stands out and get noticed. The male orange-spine (from the attached picture) can be easily identified based on the long trailing filaments that extend out from the tip of the tail fin (both top and bottom) while the female seems to be lacking this feature. In terms of general care for the orange-spine, all the requirements are almost similar like the other unicorn cousins but be sure to watch out for outbreak of disease especially ich or white spot in which they are particularly susceptible to. Finally, if you happen to come across one sold at pet shop, make sure you don’t miss the chance to get one for your marine aquarium.
Some other saltwater aquarium stocking options:
Miniatus Grouper single-species tank
Some other saltwater aquarium stocking options:
Miniatus Grouper single-species tank
