Nonapeptides play a fundamental role in the regulation of social behavior, among 
numerous other functions. In particular, arginine vasopressin and its 
non-mammalian homolog, arginine vasotocin (AVT), have been implicated in 
regulating affiliative, reproductive, and aggressive behavior in many vertebrate 
species. Where these nonapeptides are synthesized in the brain has been studied 
extensively in most vertebrate lineages. While several hypothalamic and 
forebrain populations of vasopressinergic neurons have been described in 
amniotes, the consensus suggests that the expression of AVT in the brain of 
teleost fish is limited to the hypothalamus, specifically the preoptic area 
(POA) and the anterior tuberal nucleus (putative homolog of the mammalian 
ventromedial hypothalamus). However, as most studies in teleosts have focused on 
the POA, there may be an ascertainment bias. Here, we revisit the distribution 
of AVT preprohormone mRNA across the dorsal and ventral telencephalon of a 
highly social African cichlid fish. We first use in situ hybridization to map 
the distribution of AVT preprohormone mRNA across the telencephalon. We then use 
quantitative real-time polymerase chain reaction to assay AVT expression in the 
dorsomedial telencephalon, the putative homolog of the mammalian basolateral 
amygdala. We find evidence for AVT preprohormone mRNA in regions previously not 
associated with the expression of this nonapeptide, including the putative 
homologs of the mammalian extended amygdala, hippocampus, striatum, and septum. 
In addition, AVT preprohormone mRNA expression within the basolateral amygdala 
homolog differs across social contexts, suggesting a possible role in behavioral 
regulation. We conclude that the surprising presence of AVT preprohormone mRNA 
within dorsal and medial telencephalic regions warrants a closer examination of 
possible AVT synthesis locations in teleost fish, and that these may be more 
similar to what is observed in mammals and birds.