Even though it is known to be a cannibal, the mangrove rivulus or killifish of the Americas will never eat one of its own embryos, even if it is hungry. This slender amphibious fish can recognize its own kin, even if these are still in the embryonic stage. This is according to a study by Michael Wells and Patricia Wright of the University of Guelph in Canada, in Springer’s journal Behavioral Ecology and Sociobiology.