Species Profile: Upside-down Jellyfish (Cassiopea sp.) in the Home Aquarium

Eileen here.

One of the most iconic images of a jellyfish, the one most people think of, is that of a dome-shaped animal with long flowing tentacles drifting through the water. For the aquarium community however, this is not the one that we usually see in our tanks. A far more common aquarium jellyfish is the Upside-down Jellyfish.

There are about five different species of Upside-down Jellyfish, found mostly in the Caribbean and tropical western Atlantic Ocean. One of these species in particular, Cassiopea andromeda, has made its way to the Hawaiian Islands and seems to have established itself as a nuisance in waters around the state. It is another species, Cassiopea frondosa, that is usually found in the aquarium trade.

All jellyfish are planktonic by nature, meaning they move with the flow of the water instead of swimming against it. The Upside-down Jellyfish does not actually live in the water column like most other jellyfish. Instead, they use their bell much like an anemone uses its foot to attach to the bottom of a shallow environment like a lagoon, mangrove swamp or sand flat. While this attachment isn’t nearly as strong as an anemone, it helps the jellyfish to remain relatively stationary with its tentacles pointed up towards the surface.  The bell will often pulsate slightly to create a weak water flow over its tentacles which the jellyfish uses to filter-feed small food particles from the water. Upside-down jellyfish also have stinging cells known as nematocysts on its tentacles which it can use to stun larger prey. This feeding helps supplement its diet, but most of the jellyfish’s nutrition comes from the symbiotic algae in its tissue. The sunlight filtering through the water feeds the algae, which in turn produces food for the jellyfish while the jellyfish provides protection for the algae by keeping it alive in its tissue.

Upside-down Jellyfish are one of the easiest types of jellyfish to keep in home aquariums but still require special care and attention. As these animals can reach a diameter of almost a foot across, they should have plenty of flat, open sandy area to spread out. They also need very bright light to feed the algae in its tissue as well as periodic target feeding with foods like brine shrimp, baby brine shrimp, cyclops, zooplankton, phytoplankton and dissolved organic foods. The flow in the tank should be moderately low and any filter intakes should have some sort of covering to make sure the jellyfish doesn’t get sucked up by the current. The stinging cells on their tentacles can also harm other tankmates; do not keep with any shrimp, gobies or other invertebrate or small fish that can become food! These nematocysts can also sting aquarists so take care not to come into contact with the tentacles.

The flower-like appearance, unusual behavior and relatively easy care are making this jellyfish gain in popularity among home aquarists. With some extra TLC and research, Upside-down Jellyfish can truly be a unique addition to a home aquarium!

Archerfish – Aquatic Snipers

Patty here. archerfishOften brackish fish are a hard sell to people on the market to start an aquarium.  Fish appropriate for brackish systems don’t tend to be as colorful or as easy to mix in communities as many other types of fish, or so many think.  But though these fish are often banished to a remote corner of the fish shop, and often seem too complicated to keep, there is one fish in particular that may be the one to convince you to try your hand at a brackish system.

Archerfish are a common offering in the trade, but their brackish classification and simple beauty may keep them hidden from the view mainstream aquarium enthusiasts.  They are native to India, Southeast Asia, Australia and other countries of the western Pacific.  They prowl through estuaries and mangroves mostly, but may be found upstream in full freshwater or on reefs periodically.

The Banded Archerfish (Toxotes joculatrix), the species commonly offered in the trade, is modestly colored with a tan-grey dorsal area and a pale silvery-white body.  Bold black markings camouflage them from prey and predator above.  They have a compressed body with a flat area from the dorsal fin to the mouth which allows them to move along just under the surface of the water. The mouth is angled upwards.

The most fascinating thing about Archers is their unique and famed ability to shoot their prey.  These fish are skilled predators that are able to snipe insects from branches and foliage 3-5 feet above the surface.  The fish shoots several droplets of water, quickly correcting any error in trajectory and aim to knock prey from the safety of the canopy to the water’s surface where the fish devours its meal.  They may also leap from the water to catch prey that is within reach or dine on small shrimp and fish in the water, but in the wild they commonly swim in groups of “shooting parties”, working together to pick off unsuspecting bugs. With the right set up, you can witness this behavior in your own living room!

This species can reach a max size of up to 12 inches in the wild, so habitat size is the first thing to consider.  They can be expected to reach about 8-10 inches in captivity, and the minimum size aquarium is 55 gallons.  Larger, deeper tanks are better!  Though juveniles may tolerate freshwater environments for some time, as the fish mature a brackish level of 1-2 percent will be necessary (roughly 8-15 teaspoons of aquarium salt per 10 gallons).  The ideal set-up is one that allows for plenty of room to swim and terrestrial areas or areas of open air (like a large tank filled half or 3 quarters full/paludarium set-up) to make the fish happy and allow for a great show! 

You can furnish the tank with salt tolerant vegitation both in terrestrial areas and submerged, driftwood, root wood, rock, and sand or fine gravel.  Good filtration is a must! Though the fish are hardy, they like clean water like that where they are found in the wild.  Once in their new home these fish will quickly resume normal hunting activities, and a batch of live crickets will make for some sport.  These fish will also eat frozen and freeze-dried foods.  Other fish can also be housed with archers as long as they are tolerant of brackish conditions, large enough not to be considered prey, and not overly boisterous.

Freshwater Shrimp: an Overview of Popular Aquarium Species – Part 1

Hello, Frank Indiviglio here.  Until recently, freshwater shrimp have largely been ignored in the US aquarium trade. I’ve kept a few native species over the years, and was awed by some huge, long-clawed specimens that I collected and released in Costa Rica.  But it wasn’t until I visited Japan several years ago that I became aware of the scores of small, colorful Asian and South American shrimps that were being bred and sold regularly there.  Happily, most of those I came across at that time are now well established in the trade here in the USA.

Environment and Tankmates

The following shrimps will co-exist with one another, provided the dietary needs of the specialists are met.  All thrive at temperatures of 74-80 F and a pH range of 6.5-7.5.  They do best in heavily planted aquariums with moderate water flow and, like many invertebrates, are very sensitive to ammonia.  Many species appear somewhat social, congregating together, and most gravitate to and forage on driftwood if such is provided. 

Freshwater shrimps may be housed with small, peaceful aquarium fishes, but will be attacked buy predatory species and crayfishes.  I have had very good luck in keeping breeding groups with guppies, armored cats (Corydoras spp.) and hill stream, coolie and yo-yo loaches.

Feeding Shrimp

All the following species consume algae, with some favoring hair algae, but they also take a wide variety of flakes, pellets, carrion and organic detritus.  Shrimp of all types are seemingly always foraging, day and night, and should be provided with a wide variety of food options. 

In addition to live algae, I offer freshwater shrimps tropical fish flakes, shrimp pellets, spirulina tablets and live brine shrimp.  If water quality is not an issue, it is also a good idea to allow them to feed upon an occasional small, dead fish.

Amano or Japanese Marsh Shrimp and Relatives, Caridina multidentata

This East Asian import was one of the first species established here, and is still a favorite.  Please see the article referenced below for further information.

The closely related dwarf blackberry shrimp and emerald green shrimp, both native to Thailand, are beautifully patterned and may hybridize with the amano shrimp.  All three prefer to feed upon hair algae, but will take a wide variety of other foods.

Bumblebee Shrimp, Caridina trifasciata

Another Japanese import, the bumblebee is strikingly marked in black and white and possessed of a squat build that makes it seem larger than its ¾ inches.  Voracious scavengers as well as algae eaters, a group of these beautiful shrimps makes a spectacular display.

Orange Halo or Bee Shrimp, Caridina sp.

Favoring hair algae, this native of Thailand is bright orange in color and reaches ¾ inches in length.  In common with its relatives, the orange bee shrimp does best in groups.

Pearl or Snowflake Shrimp, Macrobrachium mirabile

A giant among the dwarf shrimp, this long-clawed species may top 2 inches in length.  It hails from India, where it favors the brackish water of river mouths.  Captives do fine in freshwater, however, and make excellent scavengers.  Despite its size, it is inoffensive to its smaller cousins.

Further Reading

For information on keeping the popular amano, cherry and bamboo shrimps, please see An Introduction to Freshwater Shrimps.

To learn more about a truly unique shrimp, please check out my article Keeping the African Giant Filter Shrimp.

Next time I’ll cover a few species that are rather new to the trade, as well as some more colorful and unique favorites.  Please write in with your questions and comments.  Thanks, until next time, Frank Indiviglio.


Common Fish Diseases and Conditions

There are four main categories that fish diseases can be divided into: Bacterial, Fungal, Parasitic, and Environmental. Some conditions can be caused by more than one of these (like secondary fungal infections at the site of a bacterial infection, or bacterial infections caused by poor water conditions) and identifying the cause of the issue is often important to helping to resolve it. 

Some general information on these types of conditions:

Bacterial Infections:  Bacterial infections are some of the most common and widespread conditions in aquariums. They may looks like a rough white coating, red patches or red sores, frayed or deteriorating fins, cloudy eyes or other similar visible symptoms depending on the exact bacteria. The edges of sores may be white and fuzzy, especially in the case of a secondary fungal infection also affecting the site. General bacterial infections are usually caused by a wound or injury, or poor water conditions like high Ammonia or low pH. They may be worse in fish already stressed by transport, bullying by tankmates or poor or improper water parameters. It is important to get rid of any causes of the infection or any conditions that may be making it worse. ALWAYS test the water quality to make sure the pH and temperature are appropriate and the Ammonia and Nitrite levels are zero or very minimal; fix any levels that are off before attempting to treat or medicate. If the water quality is good, a medication can be used if necessary. Some infections will clear up on their own once the conditions are improved but some mild medications or dietary supplements can help the healing. In severe cases or with some tankmates, a stronger medication might be needed and should be done in a separate quarantine system.

Fungal Infections:  Fungal infections usually look like a cottony patch on a fish, particularly around the edges of a wound. Waste like leftover food can also grow a fungus, as can ornaments that are improperly cleaned. Using some air fresheners, cleaners or oils in the vicinity of the tank can also cause a white coating to grow on surfaces. It looks like tufts of cotton and can appear anywhere on the fish, particularly around an existing wound. Fungal infections are usually a secondary condition that appears because the fish is already weakened by another problem. Slow-moving fish like Bettas are vulnerable to a body fungus if the water is too cold for the fish to remain active or if the fish’s metabolism is slowed. Wounds may have a secondary fungal infection around the edges, especially if the water is dirty. Waste or decorations may grow a fungal coating if the water flow is too low to move the waste so it can be removed by the filtration. Improve the water flow, temperature, water conditions or other parameters that may be allowing the fungus to grow. Medication can be used in some cases but most mild fungal infections will clear up on their own once the cause is addressed. 

Parasites: Parasites in general are one of the most common aquarium maladies next to unsuitable water conditions. Parasites by definition are any organism that requires a host organism to live, often to the detriment of that host and may lead to the death of the host. The size of parasites varies greatly from tiny organisms like those responsible for Ich and Marine Velvet, to larger crustaceans and worms like flukes, anchor worms or fish lice. These parasites can also be external (living on the outside of the body of the fish) or internal (living inside the fish, often in organs like the digestive system). Common signs of parasites are rapid breathing, weight loss, white feces, sores or a flicking or scratching behavior against rocks and surfaces. Different parasites require different treatments and treatment methods and so should be carefully diagnosed before medicating or treatments.

Environmental Stress/Biological Conditions: Environmental stress can result from improper water conditions (temperature, pH, salinity, etc.), unsuitable decor (too much or too little vegetation or decorations, too intense or dim lighting, etc.) or exterior conditions like activity in the room around the tank or vibrations caused by an unstable surface or tapping on the tank. Some biological conditions like poor nutrition, improper diet or poor breeding can cause problems as well. Some of these stresses can be easily fixed while others can be more difficult. Poor health or unusual behavior (including jumping from or trying to jump from the tank) can hint towards something wrong with the fish’s environment. Researching all choices for an aquarium and observing behavior regularly can help an aquarist to notice these problems.

Some more specific diseases and conditions that aquarists commonly encounter: 

 B  : Bacterial,  F  : Fungal,  P  : Parasitic, E : Environmental/Biological) 

Ammonia Burn ( E )As the name suggests, this is a burn-like injury caused by highly acidic ammonia build-up. Ammonia can cause open wounds on a fish’s body or damage to sensitive structures like their gills. These excessive ammonia levels are commonly caused by poor filtration or overstocking with too many fish or fish too large for the tank. Treatment includes eliminating the cause of the high ammonia level, neutralizing or removing the ammonia, and treating the wounds if necessary to avoid infection. 

Aeromonas ( B ): Aeromonas infections are caused by several species of bacteria that are opportunistic and will affect organisms with weakened immune systems. It can affect fish, amphibians and even humans in some cases. Koi and other pond fish are vulnerable to Aeromonas infections during the early spring and summer when temperature fluctuations can leave them vulnerable and weakened. Aeromonas attack organs and will digest gelatin and hemoglobin cells. It often appears as deep open sores on the body of a fish as well as causing severe weight loss as it attacks the internal organs. Aeromonas bacteria is very resistant to most medications and can be very difficult to treat. Strong gram-negative bacterial medications both in the water and in food treatments can be used. Injections are also sometimes used by veterinarians and biologists to treat larger fish.

“Black Ich” or “Black Spot” ( P ): This disease is a parasite infection caused by flatworms. It mainly affects tangs and surgeonfish and appears as small dark spots on the body of the tang. The fish may also flick or scratch against surfaces or may be less active than normal. The flatworm lays eggs on the body of the fish and drops off within a few days, leaving the eggs to hatch on the fish a few days after that. Treatment for Black Ich can include freshwater baths or antiparasitic medications with active ingredients like formalin.

Brooklynella ( P ): This parasitic infection is also known as “Anemonefish Disease” or “Clownfish Disease” due to its most common victim. It is a protozoan that usually spreads very quickly and is almost always fatal and has no commercially-effective treatments. It can first be seen as a fine sheen on the affected fish – usually newly captured or transported fish – but soon evolves to signs of physical stress to the fish, difficulty breathing, and excessive slime coat production. As this slime coat sloughs off the fish, it can spread the protozoans throughout a system to prompt quarantine of an infected fish is absolutely important. All tank equipment should be cleaned and sterilized well as well to avoid spreading the disease. As I mentioned, there are no medications that are known to be very effective on these protozoans, but medications like those containing formalehyde, malachite green and and methylene blue used in a quarantine tank can help. Do not use freshwater dips with this infection.

Columnaris/”Mouth & Tail Rot” ( B, F ): With this bacterial infection, the “tips” of the fish – lips, mouth, and tail – are affected first. They develop a milky-white coating and appear to “rot away”. It may be accompanied by a cottony-looking secondary fungal infection. In some fish – Rainbowfish especially – the gram-negative Columnaris bacteria responsible for this condition cause saddle-like patches starting at the back and dorsal fin and extending down the sides of the fish. Both of these forms may appear at the same time or you may only see one at a time. Poor water quality or sudden changes to their environment can leave fish vulnerable to this bacteria. It is important to improve any of these negative conditions before treating, and if medicating, be sure to use a medication for gram-negative bacteria. 

Dropsy ( B, E ): This is an internal condition that causes multi-organ failure, and is very difficult to treat. It is usually caused by an internal bacterial infection that causes the fish to retain fluids internally but can be brought on by other conditions or environmental stress. The fish often look like “pine-cones”, with their scales sticking out, off of their body. They are often listless, won’t eat, and sit at the bottom or in one area of the aquarium. Remove this fish as soon as you can and treat it in a quarantine tank! If the fish is eating, treat its food with an antibiotic. If not, treat the tank water with a strong antibiotic and hope for the best. If dropsy isn’t caught in its early stages (lethargy, swollen abdomen, swimming in a bizarre manner) it is almost always fatal.

“Fin Rot” ( B, F, E ): Fin rot can be more of a symptom than a disease in some cases (outside of the Columnaris/ “Mouth & Tail Rot” described above) and is essentially just what the name describes. The fins on the fish, most often first noticed in the caudal (tail) fin, will appear to be rotting away and may be red and ragged. The fins may also appear white as a secondary fungal infection sets in in some cases. This is usually caused by a bacterial infection and can be the result of bullying or fin-nipping tankmates or poor water conditions. The cause of the condition should be address (water quality improved or aggressive tankmate removed) and the fish can be treated with an antibiotic or antibacterial medication.

Head and Lateral Line Erosion (HLLE) ( E, P ): Head and Lateral Line Erosion (HLLE) is seen mostly in saltwater tangs and angelfish but other fish are also susceptible. Another similar condition, known as Hole-in-the-head, is very similar in appearance but mainly affects large cichlids and freshwater fish. With HLLE, the area around the head and eyes and the length of the lateral line down each side of the fish’s body becomes pitted and can appear to be rotting away. While not usually fatal in itself, HLLE can cause permanent scarring and is a symptom of a more serious and ongoing condition like poor nutrition. Fish like tangs that are especially vulnerable to this condition should be fed a varied diet high in fresh macroalgae. Vitamin supplements can also be helpful. Some research suggests that HLLE can also be caused at least in part by other stresses like some flagellate parasites or stray electrical current.

Hole-in-the-head Disease ( E, P ): Hole-in-the-head is very similar to HLLE, described above. Some aquarists argue that these two names refer to the freshwater and saltwater versions of the same condition since they share some of the same causes and symptoms. Hole-in-the-head is found mostly with large cichlids like Oscars and Discus but can affect other fish as well. Like HLLE, the main cause is usually linked to improper diet or water conditions and adding vitamin supplements and a varied diet can often help stop and reverse some of the effects of the disease. Hole-in-the-head is also attributed more to parasite infections than HLLE, specifically protozoans.

Ich” ( P ): Ichthyophthirius multifiliis, also known as Ich, Ick, or White Spot, is one of the most common and well-known conditions in the aquarium hobby. Many aquarists incorrectly diagnose problems with their aquarium as ich when it is actually another condition. Ich is a parasite that affects freshwater fish (as opposed to the similar Cryptocaryon that affects saltwater fish but has an almost identical appearance, symptoms and treatment). Ich appears as small white spots on the body of the fish. These spots look like grains of salt as opposed to the cottony tufts of fungal infections, the dust-like appearance of oodinium or some bacterial infections or the pits associated with Hole-in-the-head and HLLE. The fish may stop eating, may scratch and rub against surfaces, and may appear lethargic. Treatments include increasing temperature, adding vitamin and garlic supplements, freshwater or saltwater “dips”, and a score of medications. The parasite also has a life cycle that allows it to remain dormant in an aquarium or on a fish for weeks at a time before blooming when triggered by environmental conditions or the fish’s immune system being weakened by stress or anther condition. Some medications available to treat ich are not safe for all fish or for invertebrates; be sure to choose the medication suitable for your aquarium. 

Internal Parasites ( P ): Internal parasites can be diagnosed externally by white, stringy feces and a sunken stomach or eyes as the parasite steals the nutrients from the fish. Internal parasite – most commonly types of worms – can affect the fish most commonly from infected live or fresh foods. External medications that are added to the water are less effective on internal parasites. It is best to treat the fish’s food by soaking the food in a medicated solution before feeding. Garlic supplements and other vitamins also may help expel the parasite and help the fish replenish its nutrients and fight off the parasite on its own. 

Lymph” (Virus): Lymphocystis, commonly known as “lymph”, is a virus that affects both freshwater and saltwater fish. This virus forms white cauliflower-like growths on the fins and body of the fish and can cause white patches around the eyes. It usually develops when the immune system of the fish is weakened due to poor nutrition or water quality. Being a virus, there is no reliable medication to treat it but improving the conditions and diet will help to boost the fish’s natural immune system and can help the fish fight it on their own. Some sources recommend removing the nodules by scraping them from the body or fins; this can be a dangerous approach that may lead to excessive stress and secondary infections. Lymph is not usually fatal and often may clear up on its own as the fish fights off the virus.

Marine Velvet/ Oodinium ( P ): Marine Velvet, also known as Oodinium, is caused by the parasite Amyloodinium ocellatum. This is one of the most fatal parasitic infections as it is very contagious and resistant to most medications. Marine Velvet looks like a very fine velvety coating on the fish as opposed to the salt-like spotting of Ich. The fish may also breathe rapidly and have cloudy eyes. Quarantine and treat any affected fish as soon as possible with a strong antiparasitic treatment like copper sulfates. The salinity can also be lowered and a UV sterilizer can be used to help kill the parasites.

“Neon Tetra Diseases” (NTD) ( P ) Despite the common name, this condition affects many more species than just Neon Tetras; most freshwater fish like tetras, danios, rasboras, rainbowfish and more can be affected. It typically first appears like a saddle extending around the dorsal fin on the back of the fish similar to the Columnaris infection described above. Rather than the fuzzy, wispier look to Columnaris patches, NTD looks more like the color and scales have been “erased” from the area. The fish may swim erratically or its body may start to appear bend downward at the spine.  NTD is caused by a Microsporidian parasite. This is an internal parasite that starts affecting the fish from the inside rather than the external parasites like Ich more commonly encountered. This parasite can be highly contagious and is usually spread by eating infested foods or fishflesh. There is no effective treatment for this condition. Once a fish shows symptoms, it is best to move it into a separate quarantine system or euthanize it to avoid spreading the parasite to other fish. 

Pop-eye ( B, E ): Like the name suggests, “pop-eye” is a condition in which one or both eyes of the fish appear to be swollen and popping out of the socket. This can result from a bacterial infection, poor water quality, injury or in rare cases a gas pocket in the eye socket. This is typically a symptom of an underlying condition like poor water quality and is difficult to treat specifically. Anti-bacterial medications may help but the water quality and any other possible causes should be addresses as well. Pop-eye may often clear on its own but may lead to decreased vision in the affected eye.

Scar Tissue/Cysts ( E ):  Sometimes confused with Ich, these irregular lumps are usually only along the spines in the fins. They are caused by a blood vessel blockage or scar tissue due to broken spines, poor breeding, poor water quality, or stress. It can sometimes – but not usually – be an early sign of or lead to a secondary disease like Fin Rot. They are usually seen in fish with larger fins like Angelfish, Guppies, Bettas or selectively-bred longfin varieties of other fish. Usually benign and harmless, they are not usually treatable but usually disappear on their own.

Septicemia ( B, E ): Septicemia is an infection in the blood. The infection itself is bacterial but usually occurs when a fish is left vulnerable due to poor water conditions. It appears as red streaks in the fins and body and open sores or deteriorating fins in more severe cases. Any environmental conditions like poor water quality must be improved and resolved as quickly as possible. External bacterial medications in the water may help but pretreating the food with medication and using internal bacterial medications is more effective. Catching this infection as soon as possible drastically improves survival rates.

Swim Bladder Infection/Disorders ( E ): This condition is seen mostly in fancy goldfish, balloon mollies and other fish bred for a similar “chubby” body shape. The swim bladder in fish is used to help control buoyancy (the up and down motion) through gas exchange within the fish’s body. The fish is considered “neutrally buoyant” when it is able to hover in the water without floating up or sinking down. If the fish is unable to achieve buoyancy, it may float, sink or be unable to swim properly or remain upright in the water. This may be the result of an internal bacterial infection that can be treated with some medications. Some fish, especially fancy goldfish, may gulp air at the surface will feeding and have similar issues caused by air in their digestive systems. Feeding them fresh greens like peas or zucchini may help get rid of this bubble.

Introducing the Boxfishes, Trunkfishes, and Cowfishes

Hello, Frank Indiviglio here.  With rigid bodies propelled “helicopter fashion” by tiny fins, the 33 marine species that comprise the Family Ostraciidae are quite amusing as they motor about.  Their appeal is heightened by an “alert” face and, in many, horn-like projections at the head and rear.  Some species grow quite large and require unique diets, but several make interesting, appealing aquarium subjects.

A hard bony carapace protects cowfish relatives from attack by many predators.  However, all are slow moving, and their rapidly undulating fins seem to draw attacks from smaller fish.  Oddly enough, the skin over their rigid protective plates is quite sensitive.  Be sure to watch your specimens closely, lest wounds inflicted by tiny fishes go un-noticed and lead to infection or stress-related diseases.

A 40+ Year Old Memory of a Long Horn Cowfish, Lactoria cornuta

A brilliant yellow body highlighted with blue spots and set off by “horns” at the head and rear renders this droll fish instantly recognizable.  I have a soft spot for these comical fellows.  Back in the early 1960’s, when my grandfather lured me into keeping marine fishes, a long horn cowfish was my first exotic species.  Armed with pioneering marine aquarist Robert Straughan’s 1959 classic The Salt Water Aquarium in the Home, we frequented the 2 NYC aquarium stores (1 in the Bronx, 1 in lower Manhattan) that stocked marine fishes.  Shipments were irregular at the time, but we lucked out on 1 trip with a gorgeous cowfish. 

All-glass tanks were not yet available, so we installed our prize in a large plastic aquarium, where he impressed me greatly by being the only one of  my early purchases to survive my clumsy attempts at marine fish husbandry! 

Slow feeding and peaceful (although aggressive towards other cowfishes), the long horn is one of the few fishes that I was able to house with another long-time favorite, the Atlantic seahorse. 

Hovercraft Boxfish, Tetrosomus gibbosus

This species’ mode of swimming truly fits its name, with only the fins fluttering, propeller-like, as the rigid body moves along.  They are extremely inquisitive, seeming to notice and examine all happenings within and outside of their aquarium.

Maturing at a mere 4 inches in length, hovercrafts are an excellent choice for those lacking space to house long horn cowfishes and other large species.  They are, however, slow to feed, and so their condition should be monitored closely…the stomach areas of underfed boxfishes will rapidly take on a sunken appearance.  However, when housed with other small, methodical feeders (seahorses and pipefishes are worth a try), hovercrafts do quite well.

Husbandry Considerations

Many cowfish relatives are, despite their “apparent calmness”, quite excitable.  Frightened specimens will release a skin-generated poison into the water.  Known as ostracitoxin, this secretion is toxic to other fishes, and, in close quarters, to the toxin-producer itself. 

Establishing cowfishes in an aquarium before adding other species, and choosing only slow-moving, peaceful tank-mates, will go a long way in preventing disasters.  In a dark room, always turn a small room light on before using the aquarium canopy light.

In the wild, cow, box and trunkfishes feed largely upon algae and sessile invertebrates (i.e. sponges, tube worms).  Captives take a wide variety of frozen, freeze-dried  and algae-based foods, along with live brine shrimp, mysids and blackworms.

Further Reading

For further information on the long horn cowfish, please see Species Profile: the Long Horn Cowfish.

Please write in with your questions and comments.  Thanks, until next time, Frank Indiviglio.

Image referenced from Wikipedia and originally posted by LASZLO ILYES