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Cichlid fishes are champion caregivers that protect, clean, aerate, and sometimes even feed their young. This tropical fish family’s extensive species radiation combined with great diversity in care habits make cichlids immensely useful models for studying the evolution of parental care. In this chapter, we review the diverse ways that care is provided (~1/3 of species guard young on the ground and 2/3 mouthbrood) and the variation in sex of the caregiver (42% of species have biparental care, 58% show the derived state of female-only care). Substrate guarding, the ancestral form of care, is especially common among New World cichlids. In contrast, mouthbrooding, dominates in African clades. We also describe two forms of expanded (allo) care: (1) brood mixing where parents care for non-descendant young; and (2) cooperative breeding with joint care by an entire social group. Such cooperative breeding, arguably one of the most socially complex breeding systems, has arisen at least 5X among cichlids, all within a single clade, the Lamprologines of Lake Tanganyika. Using one well-studied cooperative species, Neolamprologus pulcher, as an example, we review the various possible explanations for the evolution of cooperative care. We conclude by discussing some exciting future directions for the study of parental care in cichlids.

The Cichlidae, one of the most diverse families of vertebrates, is the subject of the volume entitled “The Behavior, Ecology and Evolution of Cichlid Fishes” which we introduce here. Cichlids are major members of their communities. They are socioeconomically important in fisheries, aquaculture, and the ornamental trade. The immense number of cichlid diverse forms challenge researchers to integrate new tools to delineate species, construct phylogenies, and determine species diversity; and their detailed study has significantly contributed to evolution models. Cichlid researchers have a strong tradition of taking a comparative approach. This book reflects that tradition with 20 reviews written by internationally recognized experts providing an integrative sub-disciplinary perspective, often including molecular studies. This volume is broad in scope, beginning with a review of the history of cichlid studies over two centuries. Next, four reviews examine cichlid diversification at different scales in African and Neotropical lakes and rivers; followed by four on conservation and management including species delimitation tools. The midsection, covering cichlid behavioral adaptations and their underlying mechanisms and effects, concerns the senses, parental care, sociality, and neurobiology. The last part of the book includes reviews on cichlid ecology, plasticity and evo-devo and closes with an examination of cichlids as models for biomedicine.

Olfactory cues that indicate predation risk elicit a number of defensive behaviors in fishes, but whether they are sufficient to also induce morphological defenses has received little attention. Cichlids are characterized by a high level of morphological plasticity during development, and the few species that have been tested do exhibit defensive behaviors when exposed to alarm cues released from the damaged skin of conspecifics. We utilized young juvenile Nicaragua cichlids Hypsophrys nicaraguensis to test if the perception of predation risk from alarm cue (conspecific skin extract) alone induces an increased relative body depth which is a defense against gape-limited predators. After two weeks of exposure, siblings that were exposed to conspecific alarm cue increased their relative body depth nearly double the amount of those exposed to distilled water (control) and zebrafish Danio rerio alarm cue. We repeated our measurements over the last two weeks (12 and 14) of cue exposure when the fish were late-stage juveniles to test if the rate of increase was sustained; there were no differences in final dimensions between the three treatments. Our results show that 1) the Nicaragua cichlid has an innate response to conspecific alarm cue which is not a generalized response to an injured fish, and 2) this innate recognition ultimately results in developing a deeper body at a stage of the life history where predation risk is high.