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Uncommon Facts About Common Aquarium Fish


I’d like to take time to welcome Frank Indiviglio to That Fish Blog. Frank is a former Bronx Zoo Zoologist, author and conservationist who’s worked with everything from fish to elephants. He’ll share his unique insights and work with various species on here, as well as the newly created That Reptile Blog & That Avian Blog. Welcome Frank!

Today I would like to pass along some interesting facts concerning fish you may be familiar with. I’ll focus mostly on aquarium trade species, with a few others added for good measure. I’ll add to the list in future articles. Enjoy, and please share your own store of unusual facts with us.

Finding a mate in the dark, featureless expanses of the deep sea poses quite a difficulty. Male benthic anglerfishes, such as Ceratias uranoscopus and related species, solve this dilemma by biting onto the first female they encounter. Thereafter, the male’s internal organs degenerate and he remains fused, by his mouth, to the female – surviving on nutrients circulating in her blood and periodically releasing sperm to fertilize her eggs!

Unique among the world’s fishes, male sticklebacks (small fishes of the family Gasterosteidae that inhabit marine, brackish and fresh waters), use kidney secretions to glue plant materials together when constructing their enclosed, bird-like nests. This behavior, along with their zealous protection of the eggs, helped spur the development of the aquarium hobby in Europe in the 1700s.

Cichlids found in Africa’s Lake Malawi are among the most enthusiastic of nest builders. Although measuring but 6 inches in length, males of one species create circular sand mounds that can exceed 3 feet in diameter, while another excavates 10 foot wide pits. Up to 50,000 such structures may be constructed in the same general area by a displaying group, or “lek” of males.

Marine damselfish, such as Stegastes nigricans, are unique in practicing a form of underwater “farming”. Pairs form territories around beds of marine algae (“seaweed”) and drive off fishes, shrimp, crabs and other creatures that show interest in this favored food.

Clownfish, such as the commonly kept percula clownfish, Amphiprion percula (or its cousin, the false percula, A. ocellaris, of “Nemo” fame) live unharmed among the tentacles of sea anemones — marine invertebrates that sting and consume other similarly-sized fishes. Anemone tentacles respond with a sting upon contact with any alien body, but are prevented from stinging themselves by chemicals in the mucous that they secrete. The clownfish, it seems, produces the same chemical in its own mucous and hence is not recognized as food.

Fishes lack external ears but do have inner ears that pick up the water pressure changes which accompany sounds. Aided by the Webarian Apparatus, an organ that connects the
inner ear to pressure-sensitive gas in the swim bladder, species such as carp and goldfish hear quite well and can communicate through vocalizations (perhaps it is not so odd to talk to your pet after all!).

Among the animals that are kept by people for their fighting abilities, none are as small as brackish-water fishes known as wrestling halfbeaks, Dermogenys pusilla. These thin, 3 inch-long warriors are the subject of staged matches in betting parlors throughout Thailand and Malaysia. Fights rarely result in injury, except to the wallets of losing bettors!

Despite popular belief, koi, Cyprinus carpio and goldfish, Carassius auratus, are not closely related. Goldfish, the first of any fish to be domesticated, were first kept by the Chinese over 2,000 years ago. Koi (the word means “carp” in the Japanese language) originated in the Black Sea area and arrived in Japan as a food source. They were first bred for domestic traits in Nigata, in northeastern Japan, in the 1820’s.

Ichthyologists discover new facts about fish on a near-daily basis. You can read articles about their findings at:
http://sciencedailey.com/

Thanks Frank,

Until Next Time,

Dave

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Being born with a deep interest in animals might seem unfortunate for a native Bronxite , but my family encouraged my interest and the menagerie that sprung from it. Jobs with pet stores and importers had me caring for a fantastic assortment of reptiles and amphibians. After a detour as a lawyer, I was hired as a Bronx Zoo animal keeper and was soon caring for gharials, goliath frogs, king cobras and everything in-between. Research has taken me in pursuit of anacondas, Orinoco crocodiles and other animals in locales ranging from Venezuela’s llanos to Tortuguero’s beaches. Now, after 20+ years with the Bronx Zoo, I am a consultant for several zoos and museums. I have spent time in Japan, and often exchange ideas with zoologists there. I have written books on salamanders, geckos and other “herps”, discussed reptile-keeping on television and presented papers at conferences. A Master’s Degree in biology has led to teaching opportunities. My work puts me in contact with thousands of hobbyists keeping an array of pets. Without fail, I have learned much from them and hope, dear readers, that you will be generous in sharing your thoughts on this blog and web site. For a complete biography of my experience click here.