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.
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.