Described to science in 1844, it was thought there was only a single species of Asian arowana until 2003, when a team of three ichthyologists determined that there were actually four species. These had previously been considered color phases (like black leopards or jaguars, or white tigers). This classification is controversial. All populations of the Asian arowana are considered endangered, primarily due to habitat destruction. In the past, they were considered threatened by the commercial aquarium trade, but farm-raised specimens, sold micro-chipped, with “birth certificates” now supply the demand for these “Dragon Fishes”, which, in some Asian traditions, are considered to bring luck to businesses where they are kept.
Though the Silver and Black arowanas of South America, and the Asian and Australian arowanas resemble each other, and share the behavior of brooding their eggs and fry in their mouths, they last shared a common ancestor around 170 million years ago, when the great Southern Continent Gondwana began to split apart. This took place in the Jurassic period, when dinosaurs still thrived. Although Asian arowanas are endangered, South American ones are abundant, and are important both to subsistence fishing and the sustainable aquarium trade.
It appears there are no documented cases of piranhas killing people, but there have been several cases where they have eaten humans that had drowned. In general, these specialized relatives of the tetras are opportunistic scavengers. Of the 50 or so species found in South American Rivers, this one is the most familiar, and is popular in aquariums for its bright colors. If maintained in groups of less than four, piranhas are likely to eventually kill each other. They have been bred many times in captivity.
Called Arapaima in the Guianas, Paiche in Peru, and Pirarucu in Brazil, this relative of the arowana is one of the largest purely freshwater fishes in the world, reaching nine feet and exceeding 400 pounds. They have been overexploited as food fishes, so are vulnerable to extinction. These fast-growing predators surface frequently to take air at the surface. While aquarium visitors may mistake them for Alligator gars, they are not related. Their closest North American relatives are the herring-like Mooneyes and Goldeneyes.
The Tiger rockfish is named for its striped coloration. The rockfish family is one of the largest fish families found in the temperate waters of the Pacific coast of North America. Its natural range extends from Alaska to Central California and it is known to be territorial and solitary. Many members of the rockfish family have venomous dorsal spines. The Tiger rockfish prefers to hide in rocky crevices and feeds on small crustaceans and fish.