November 24, 2009—Normally shy and secretive, a male twig catfish takes center stage as he watches over his eggs at Washington, D.C.'s Smithsonian National Zoo—behavior that, in the wild, would help keep the fish-to-be from becoming a predator's lunch.
Earlier this month, one of the zoo's female twig catfish had laid between 30 and 60 eggs on the glass wall of her aquarium—which in the wild would be any open vertical surface. Her breeding partner—seen above with his pebble-like progeny—took over to guard the eggs until they hatched on November 12.
Zoo staff will carefully track the development of the newborns, since scientists haven't had much success raising twig catfish newborns in the past. The juveniles are picky eaters and, once hatched, can be hard to find even in a zoo tank, noted Vincent Rico, assistant curator for the zoo's Amazonia exhibit.
Twig catfish are native to the Amazon, Orinoco, and Paraná rivers of South America.
Scientists don't know how many twig catfish live in the wild, because the tiny, slim fish look remarkably like submerged plant debris, making them difficult to spot. (See related pictures of the world's largest catfish in Thailand.)
Wild female twig catfish lay their eggs on surfaces covered with algae, the food of choice for newly hatched fry. Adult twig catfish also munch on algae as well as the fallen plant matter they use for camouflage.
At the zoo, newborn twig catfish nibble on blanched kale, shelled peas, and sometimes the low-protein, low-fat gel the zoo feeds their parents, Rico said.
In addition to the new arrivals, ten adult twig catfish currently live at the National Zoo, although the youngsters and their parents are not in public tanks.