Highly Divergent Age‐Specific Postembryonic Developmental Constraints and Phenotypic Plasticity in Hatchery‐Reared Tropical Cloudy Damselfish, Dascyllus carneus Fischer, 1885

The proper understanding and standardization of animal growth is one of the fundamental problems in developmental biology. This means their morphology, behavior, and feeding habits will change as they develop. In this study, we integrated geometric morphometric analysis with survival modeling to examine stage-specific morphological development and mortality dynamics in the damselfish Dascyllus carneus. Binomial generalized linear modeling demonstrated significant stage-specific differences in survival probability, with mortality peaking during yolksac, preflexion, and flexion stages; periods characterized by maximum morphometric change and functional transition. Landmark-based analyses revealed significant, directional shape transformations associated with cranial development, trunk deepening, and caudal peduncle differentiation, reflecting functional maturation of feeding and locomotor systems. Shape variability was highest during early developmental stages and declined toward the juvenile stage, indicating progressive morphological stabilization. These findings demonstrate that survival is closely linked to morpho-functional development rather than size alone. Identification of critical developmental stages provides a mechanistic basis for understanding early life survival and offers practical guidance for improving larval rearing and management of ornamental reef fishes.