That Fish Blog – Aquarium Advice and Information

Sharks hold a fascination for everyone, whether they inspire fear or admiration.  They are iconic creatures many of us automatically associate with oceans, reefs, beaches and aquariums.  Though I have to say I am not a supporter of most sharks being placed in home aquariums, the possibility and temptation presents itself too often to be ignored.  Perhaps the best option is to present readers with enough information on some more appropriate species, and to encourage interested parties to research before purchase, so that these beautiful creatures will be kept in captivity more successfully.

In the vast majority of cases, captive sharks are best kept and observed in large, public aquariums, or better yet, left in their native waters to thrive.  Most species are simply too large, too mobile, and too high maintenance for the home aquarist.  If you have a VERY large aquarium, more than adequate filtration, and the financial means to acquire and support them, there are a couple of species that are less demanding that I’d like to introduce.  These species are the most common in the trade, and may be kept successfully with the right care and housing.

Bamboo Sharks, Coral Catsharks, and Epaulettes

Bamboo Sharks (i.e. Banded Catsharks) are probably the most frequently offered type of shark in the aquarium trade.  Several species are seen, they are banded brown and tan, and may have spots when they mature. Those in stores are reasonably priced and are typically sold as young pups. Egg cases are also available, allowing you to observe the embryonic shark as it develops and hatches in captivity (usually in 3-6 months). Pups are about 6 inches long when they emerge.  These sharks are native to the Indo Pacific and have the potential to grow to about 3.5 feet in length.

Coral Catsharks are a little less frequent, but they have very attractive black, tan and white patterns.  They are true tropical reef sharks, and grow to just under 30 inches in length.  They are quite docile, but should not be underestimated.

Epaulettes are very attractive, too, but they are not seen often in the trade.  These sharks are also tropical, collected from Australia and the surrounding region.  They are usually pale brown in color with dark spots all over and an ocellated black spot just behind the gills.  They reach a size of a little over 3 feet and are usually more expensive that cat or bamboo sharks.

Horn Sharks

Horn Sharks are another common type imported for sale.  Also known as bullhead or pig head sharks, these have stout bodies, a short, blunt head, with ridges over the eyes, and a prominent spine on the front of each dorsal fin.  Most often California or Mexican Horn sharks (and once in a while Port Jackson Horn Sharks from Australia) are found in pet stores.  These sharks grow to about 3.5 feet at maturity.  They are found along sandy bottoms and in kelp beds along the western coast of California and Mexico to Central America. These sharks prefer cooler water than those above (a chiller may be required), and they tend to excavate rock and substrate. 

We have 2 resident Horn Sharks here in our Touch Tank.  They spend most of their time under the rock formations in the center of the tank, but become quick and active when they smell food.  With the cooler temps, large volume and heavy filtration in the display they have grown quite fat and happy.  We’ve even found several spiral-shaped egg cases in the past couple of years!  These sharks are quite docile, with a mouth full of teeth designed to crush more than to tear. 

To Be Avoided

Several other species are seen from time to time including Wobbegongs, Dogfish, Nurse Sharks, and other even less appropriate species.  These should not, in my opinion, be offered or purchased for home aquariums  due to their large potential size, and/or special requirements.

Keeping Sharks

Sharks and egg cases should NOT be placed in tanks of less than 180 gallons (preferably larger), and the tank should be well-established. Despite their small purchase size and relatively sedentary behavior, they grow quickly and need space to move freely and turn.  The larger the tank the better (think about 3 times or more the length of the sharks adult size), furnished with some minimal rock piles and a cave where the fish can retreat and rest.  You’ll also want to supply ample flow and filtration as well as a good protein skimmer.  Even if you feel that the tank you already have may be large enough for the baby shark, or that you’ll have time to upgrade to a larger tank when necessary, it would be best to have an established tank of adequate size and function before considering a shark.

These fish will prefer their salinity on the higher side to mimic sea water, and keep it constant.  They will require regular water changes to keep their conditions pristine.  A varied diet of meaty foods should be supplied, including but not limited to shrimp, clam, krill, squid, silversides, and others (fresh or frozen, not live).  These fish can be fed 2-3 times each week, but be careful not to over feed for the sake of the shark and the water quality.  Hand feeding should be avoided to prevent accidental bites (don’t underestimate their speed or agility!).  Other fish may be housed with these sharks, as long as they are of adequate size, but be observant as some fish tend to be notorious harassers of sharks. Bottom dwellers and invertebrates like crabs, shrimp, and urchins should be avoided as they may become casual meals.  Also be aware that sharks have acute sensitivity to metals and chemicals in medications, so if a problem arises, thorough research should be performed before adding any treatment to the tank.

When you’re ready and you have carefully considered purchasing a shark, look for healthy, well-adjusted specimens that are feeding well and are not emaciated.  Avoid sharks with visible parasites or that look sunken (though newly hatched pups take a little while to fatten up).  With the right care and set-up they can be interesting and long-lived pets. 

Thanks for reading, and please let us know if you have any comments or questions about sharks for a home aquarium.

Until next time,

Patty

Shark egg cases image referenced from wikipedia and originally posted by Jean from flickr by falashad
Epaulette Shark image referenced from wikipedia and originally posted from flickr by Jim Capaldi

It has been a long-understood fact that the tranquility of aquariums has been known to help relieve stress and lower heartrate and blood pressure in some. As the biomedical field continues to grow and become more important to advancements in health care, the methods and options used by research also continue to expand. During this expansion, aquatic and marine organisms are becoming important in making advancements towards the health of all of us. Some of the fish and invertebrates you have in your home aquariums may someday help to save your life. Here are just a few of the organisms researchers have turned to:

Zebra Danio (Danio rerio): This fish is one of the most widely-used by researchers. They have become model organisms used for genetics research, neurological and other medical research, environmental studies and even organ and tissue regeneration. Specific genes have even been identified in different color pattern mutations. One of the most brightly-colored community aquarium fish, the popular Glo-fish, is a variation of the Zebra Danio that was original spliced with jellyfish DNA to create a fluorescent fish used to detect pollution and toxins. Zebra Danios are even on the very short list of animals that have made a trip into space!

Horseshoe Crab (Limulus polyphemus): The Horseshoe Crab is right next to the Zebra Danio in terms of the number of studies it participates in. They have compound eyes that have become important in vision research and a substance found in their blood known as Limulus amebocyte lysate (LAL) can help researchers detect bacteria and pathogens in medications and human tissue. LAL is collected in much the same way a person donates blood and the crabs can be released after collection. You can read all about them here.

Mussels: Mussels, the clam-like bivalves popular in aquariums and seafood restaurants alike, are already helping to heal wounds and have established their staying power in the medical field with their…well, staying power. Mussels used very thin filaments known as “byssal threads” to attach to hard surfaces. The adhesive that they use to attach themselves to surfaces is similar to the “Krazy Glue” and superglues that we all use to piece together broken mugs at home, but is much more effective in the salty, wet environments where the bivalves live. This adhesives is also extremely strong but still flexible. Researchers at companies like Johnson and Johnson have developed glues from the byssal thread compounds (warning: some graphic surgical images) that help to seal wounds and reattach bone fragments without the use of foreign materials like stitches and sutures.

Mantis Shrimp: This notorious group of invertebrates has earned a bad reputation in the aquarium industry as the secretive live rock hitchhikers known to pick off tankmates or even break aquarium glass, all while earning a following with a select few as an original showpiece. Among researchers, their powerful strikes and extremely complex eyes have made them the subject of many studies. The strike of a mantis shrimp is one of the most powerful and fastest strikes in relations to their size and researchers have studied their mechanics to discover how this power is possible. The eyes of the mantis shrimp can convert polarized light wavelengths and function over almost the entire light spectrum from infrared to ultraviolet, a feat our own eyes can’t even come close to. Their ability to convert and filter light across this spectrum has led researchers to look at mantis shrimp as the next step in optical devices like CD and DVD systems. While most of the research on mantis shrimp still seems to be focused on the “how’s”, it is only a matter of time before scientists discover how we can use what the mantis shrimp teach us.

Platies and Swordtails (Xiphophorus sp.): These two groups of livebearers are very popular, bright little community fish but recent research has given them a much more profound meaning. These livebearers are some of the first subjects to prove that some cancers like certain melanomas are actually hereditary and can be passed to offspring. Some of the dark pigment cells in these fish have been known to multiply out of control and form cancerous tumors. Remarkably, some of these fish can actually continue to live and thrive even with these tumors – and they can reproduce and pass this condition on to their young. While some forms like the popular Mickey Mouse Platies can form melanomas in the spots by their tails, it is more apparent in fish with a lot of black in their coloration. Scientists are working to understand how this condition is passed and how the fish can continue to live with it.

Corals: In addition to providing some color to the Zebra Danios already mentioned, some corals are giving biomedical scientists some inspiration in designing medications. Scientists have recently discovered capnellene, a compound found in a species of soft corals that can be used as a painkiller and may provide relief to those suffering from Multiple Sclerosis and other neurological conditions. Some of the same fluorescent proteins used to color Glo-fish are also being applied to some cancerous cells, allowing researchers to much more easily track their spread.

This is just a small sampling of how animals that have long been popular in the aquarium trade are being used to improve health and medications for all of us. As we as aquarists work to keep our own aquariums alive and healthy, those same fish and invertebrates may be working to save our lives as well.

Thanks for reading,

Eileen

Hello, Frank Indiviglio here.  Please see Part 1 and Part 2 of this article for general information on Damselfishes and their close cousins, the Clownfishes, and for notes on the care of the beautifully-colored Percula clownfish, Amphiprion percula.

Damselfishes in the Aquarium

Damselfishes are generally small, brilliantly-colored and in near constant motion.  These characteristics, along with their general hardiness, render them quite popular with aquarists.

Despite their small size, most damselfishes survive quite well in aquariums with larger fishes.  However, most are very territorial and rather aggressive towards their own and similar species (please see below).

Taxonomy

Together with the ever-popular clownfishes, the damselfishes are classified in the Family Pomacentridae, which contains over 325 species.  Many are superficially similar in appearance but differ greatly in habitat choice, food preferences and other regards, and ichthyologists (fish scientists) describe new species regularly.

Marine Gardeners

Damselfishes seem inordinately protective of their territories, so much so that these tiny warriors will even attempt to drive off human divers!  Research has revealed that several species engage in “aquatic farming, with mated pairs protecting beds of algae, a favored food.  Thick mats of algae often grow within well guarded territories but are absent outside these territories, due to a large number of other fishes and invertebrates that feed upon algae. 

The industrious little damselfishes have even been seen to “weed” their algae beds by removing debris and, possibly, competing algae species.

Further Reading

An interesting article on the relationship between Cocoa Damselfishes, human activities, coral reef health and algae is posted here.

I’ll discuss the care of various damselfish species in future articles. Until then, please write in with your questions and comments. 

Thanks, until next time,

 Frank Indiviglio

Pom-Pom Pulsing Xenia is one of my favorite corals. Quite simplistic, in color and shape, but there is something about the pulsing action and the beauty of the polyps that ranks it in my top ten corals. There are a few different types of pulsing Xenia found in the trade, such as the Pom Pom and the Silver varieties.

Considered a pest or a “weed” to some, others find it almost impossible to keep alive. There are plenty of possibilities as to why this is the case, but it always comes down to water quality. It is thought that Xenia cannot take in food like many corals do feeding on zooplankton and phytoplankton, leaving photosynthesis as the main food source. Xenia also has the ability to absorb certain nutrients and organics from the water column when needed. Due to the rate of growth and the ability to absorb organics, some people use Xenia in refugiums with or without macro algae to export excess nutrients. Not a proven miracle worker, but something to brighten up a refugium and do some work at the same time. Not to mention a small income possibility; since Xenia has a difficult time being shipped from supplier to store due to the amount of time being in a bag, the best supplier of Xenia is from local “coral farmers”.

Xeniids, despite their tolerance to not so clean water conditions are very sensitive to lower pH levels, especially when there is a constant fluctuation in levels. This can lead to a lack of pulsing, or even to the disappearance of the colony. Temperature, lack of or too much water flow, low lighting, and even over skimmed and over filtered aquarium can lead to problems.

The other potential problem with Xenia is it’s ability to take over the aquarium. With an obnoxious growth rate, neighboring corals can quickly become the next object that the Xenia grows on, possibly choking out the individual. In this situation, removing the Xenia becomes the major problem. Simply cutting the Xenia off the coral or rock may do the trick, but it has an uncanny ability to sprout a new colony or colonies from the original piece. A Kalk paste ( a paste of kalkwasser that can be applied to invasive Xenia polyps to kill those encroaching portions) can do the trick, but must be used with extreme caution with nearby corals or with pH levels. Again, to most people this is a good problem, thriving corals can equal profit.

So the next time you are looking for a hardy, unique coral, consider giving Pulsing Xenia a try, in the right application it can really shine.

Hi, Dave back again, just wanted to share with you some of the amazing Tridacna Clams that we have been seeing over the past few weeks. The diversity of colors and patterns that we have received in recent shipments may be the best that we have ever seen. That is saying something, given that I have seen thousands of clams over the years, but every time I walk past the clams lately, I cannot help myself from stopping to admire them for a while.

The photos shown here are just a sample of some of what we have had in stock, many were snatched up before we could even get pictures taken of them.  These clams have been coming from a number of sources, both captive raised and wild stock. We have gotten some really nice farm raised T. derasa and T. squamosa from ORA (oceans reefs and aquariums). The Derasa Clams in particular have had really nice color patterns.

We received some really amazing T. maxima clams that were wild harvested from Tuamota, a chain of island atolls in French Polynesia. We are expecting a new shipment of these Maxima Clams in the coming weeks, which we are eagerly awaiting. We only got a few of these specimens from the last batch that were imported, and were sorry we did not get more. These may have been the nicest Maxima Clams that I have ever seen.

We have started to see T. crocea clams become available again, they had become scarce earlier this year. Most of the Crocea Clams in the hobby are coming from Vietnam these days. These wild harvested clams have been coming in a nice variety of sizes and color morphs.

Check out our YOUR CHOICE section of our livestock page in the coming weeks for all of our WYSIWYG clams and animals, as we get some more of the beauties in stock and up for sale.

Hope that you enjoyed the photos of some of our clammy eye candy!

Dave