The Cowrie: Reef Safe or Not?

The cowry represents over several hundred recognized species of snail, and makes up the family Cypraeidae. Often times beautifully detailed with various colored spots and blotches seemingly painted on their egg shaped shell then covered in a glossy finish. The most commonly encountered cowry is the Tiger(Cypraea tigris). This shell can be found in many peoples curio decor in their home by avid shell collectors and is also probably the easiest of the cowries to purchase for their captive aquarium set-up. These snails hail mainly from Hawaii and the Indo-Pacific region of the world.

Cowries, as a whole, are herbivores that will be found combing the sandy bottoms of their natural habitat for algae and other forms of vegetable matter. They will perform the same function in a captive environment such as a reef aquarium for the most part though care must be taken as they are not considered to be 100% reef safe, but then again, what really is? Most of these snails are not recommended as an aquarium resident due to their carnivorous nature. They will feed upon sponge, corals, anemones such as Discosoma and Tunicates(ascidians). Sometimes these cowries will be mislabeled as to be considered one of the "reef safe" species of cowrie when, in essence, they should not be added as this particular cowrie is a carnivore, grows large and cumbersome and is not the species of cowrie that they say it is! For those of you with hopes of purchasing and maintaining one of the better suited cowries for the aquarium trade, such as the Chestnut(Cypraea spadicea), Gold Ringed(Cypraea annulus) and Snakehead(Cypraea caputserpentis), the addition of algal matter such as romaine lettuce, seaweed, formula two flake food, pellet style vegetable food, and spirulina are accepted and beneficial to the overall health and success of these snails. They will continuously graze on both macro and micro algae in your tank as well as feed on diatoms, which is an added bonus with the purchase of one of these cowries. Having a constant supply of vegetable matter in your tank housing one of these snails will go along way in the long term success of maintaining a cowrie in a captive environment without it dying of starvation.

As I mentioned earlier, most cowries do not make good tank mates. If you have a fish only tank, you could get away with a larger selection of these colorful snails without fear of having your prized collection of corals, sponge and other life forms being decimated. Some of these species grow to large and cumbersome in reef term genre. Similar to many urchins, their constant combing of the bottom of your tank and live rock could pose serious problems if your corals get knocked over or live rock falls down possibly landing on other life forms, injuring if not killing them. For the most part the cowry grows to a couple inches in size, though some of the larger species will obtain 4 inches in size.

The cowry is very critical of less than optimal water parameters and will surely die if not controlled. Salinity, pH, alkalinity, ammonia, nitrite and nitrates are the most crucial parameters that should read zero for the last three parameters and the first three should be stable and within range as well for the best results and health of your cowrie. Shipping of these snails tends to be difficult due to the high dissolved oxygen required by these snails.

Cowries are egg-shaped with the opening of the shell containing teeth as a form of defense. They also have a Mantle similar to Tridacna clams that extends through the opening of the shell and covers most of its exterior shell. Cowries use a "foot" for mobility in combing about the reefs and aquariums as well. Their foot is usually white, pink or cream colored and can measure twice as long as their shell. They also have antennae that enables them to search and locate food.

Their are snails in the family Ovulidae, that closely resemble and related to the true cowries. However, these snails are NOT to be housed in an aquarium as they are predatory and parasitic in nature! These include the sometimes seen Flamingo Tongue, Egg cowries and Shuttle shells. Many times these snails enter our tanks as hitchhikers, and use camouflage to blend into their surroundings to remain undetected by the natural, normal observer. Only after some time and the deterioration of your gorgonians, corals, hydroids and other valued life forms do you notice that you have an unwanted guest. These specialized predatory feeders are never recommended for the reef biotope, even though they are colorful and unique invertebrate. One side note that I should mention is that one of the most frequently seen cowrie in the curio and shell trade as well as that of the aquarium hobby is the Tiger cowry(Cypraea tigris). This is another snail that should not be included in the aquarium hobby as they obtain a large size, poses the possibility of feeding on meaty matter as well as corals, bivalves and sponges. It is unfortunate as they are gorgeous in color and are frequently seen in the pet shop industry.

As is the case with most invertebrates, being able to identify what you truly have or plan on purchasing as well as researching their husbandry and compatibility requirements, will aid your ability of maintaining these wonderful and diverse animals without sacrificing your collection of prized livestock. The cowry is yet another animal that COULD be a welcome addition offering the conscientious hobbyist another unique organisms to diversify his/her reef representation.