Preface: Advances in Cichlid Research V: Behavior, Ecology, and Evolutionary Biology

The current special issue is the fifth in a series of special issues published in Hydrobiologia exclusively devoted to cichlid fish research. The freshwater fish family Cichlidae accounts for approximately 10% of today’s teleost diversity and is naturally distributed from southern North America to southern South America, across most of Africa, to Madagascar and India. Their tremendous diversity in morphology, behavior, and ecology, as well as their astounding speciation rates and numerous species-rich adaptive radiations have enthralled biologists for decades (e.g., Boulenger, 1898; Kosswig, 1947; Fryer, 1960), such that cichlids are now among the prime model systems in evolutionary biology research (e.g., Salzburger, 2018). We are pleased to present a collection of 19 papers that investigate questions of taxonomy, biogeography, morphology, behavior, physiology, and parasitology. Many of the key ingredients of cichlid diversification are addressed by these studies, including mating, brood care and social interactions, color pattern, and body shape, as well as adaptations of the visual system and the trophic apparatus. Papers are summarized below in the order in which they appear in this special issue. We hope you enjoy reading the contributions.