Aggression in juveniles is an evolutionarily adaptive behavior documented in many species, but the neural mechanisms behind these displays are poorly understood. In the Mimetic poison frog (Ranitomeya imitator), tadpoles live in small pools with limited resources and have evolved aggressive tendencies towards conspecific tadpoles in defense of these resources. Tadpoles will attack, kill, and cannibalize other tadpoles as a primary resource defense mechanism. We examined the neural basis of neonate aggression in these tadpoles by comparing individuals that were placed in aggressive encounters and individuals placed in an environment with a non-threatening stimulus. We first did a longitudinal study to determine that the tadpoles were most aggressive when they were around five or six weeks old. We then compared patterns of generalized neural activity using immunohistochemical detection of phosphorylated ribosomes and a candidate neuropeptide, arginine vasotocin, which has been implicated in aggression in other vertebrates. Vasotocin cells in the preoptic area of the hypothalamus were not more active during aggression. We then examined neural activation across several brain regions suspected to be involved in aggression: the amygdala, hypothalamus, and medial pallium. During aggression, this showed us that the medial pallium had the most neural activation compared to controls and the other brain regions. To determine what cell types influence aggression, we then used phosphoTRAP to molecularly profile active neurons in tadpoles showing aggression compared to controls. Current work is focusing on identifying distinct neuropeptides and doing brain specific knock-down to determine individual neuropeptide influence on aggressive behavior. Overall, this project is advancing our understanding of how aggression is regulated in the juvenile brain.