Mysterious and elaborated: The reproductive behavior of the rhomboid mojarra, Diapterus rhombeus (Cuvier, 1829), in Brazilian mangrove habitats

Many fish species have behavioral traits related to reproduction that aim to improve egg conditions and survival of early life stages. Here, we provide the first detailed description of reproductive strategies performed by the rhomboid mojarra, Diapterus rhombeus. We based this description on several mating events, which occurred in mangroves located in Todos os Santos Bay, Brazil. These spawning events occurred at the mangrove fringe in the month of August in 2013 and 2014, which suggests that these spawning events occur predictably in space and time. Two principal behavioral tactics were observed and involved breeding aggregation and a unique nest-clearing behavior. Following these behaviors, many fish exhibited an extreme lethargic state during which they took refuge amidst mangrove roots. Overall, these observations revealed an unexpected and uncommon set of behaviors in an otherwise well-studied species. The present study not only highlights basic gaps in our understanding of estuarine species but also suggests that future investigations are poised to yield exciting and insightful findings.