The prisoner cichlid (Amatitlania nigrofasciata), also known as the zebra cichlid, is a species of cichlid fish native to Central America. The couple builds the nest and takes care of the eggs and parental care together. A study published in Proceedings of the Royal Society B by French researchers showed that when a female is separated from her partner, she becomes "pessimistic", as if heartbroken. She finds it harder to carry out tasks afterward. This study is the first demonstration in fish of an emotional attachment to a partner. It also raises questions about the adaptive function of such attachment.