In order to survive, animals fight to compete for limited resources and so are zebrafish. Winner fish show dominancy of the aquarium territory with occasional attacks to the loser while loser fish fleet or freeze. Besides, winner fish also showed higher tendency to win a subsequent fight while loser fish tended to lose again. Such winner-loser effects are also exhibited in zebrafish. During fighting, specific neurons activity are modified according to present and previous fighting experiences. Winner and loser will be determined when the winner- and loser-state of mind are eventually reached accordingly. To identify brain regions that differentially demonstrate the neuronal status of the winner and loser fish, we examined the expression of the immediate early genes, egr1 (early growth response protein 1), which displayed differential expressions between the winner and loser fish after fighting behavior task. Egr1 is an inducible transcription factor, which is activated rapidly and transiently upon neuronal stimuli. Up-regulation of this gene was shown to involve in synaptic plasticity and learning in mammal and avian model. Without fighting, zebrafish with overnight isolation expressed egr1 in low basal level. However, upon one-to-one fighting after overnight isolation, both winners and losers showed up-regulation of egr1 in telencephalon, hypothalamus, tegmentum mesencephali, habenula, interpeduncular nucleus (IPN) and cerebellum. The expression levels in telencephalon, hypothalamus and tegmentum mesencephali regions were similar in both winners and losers. On the other hand, significantly higher expressions of egr1 were found in ventral habenula (vHb) and the granule cell layer of corpus cerebellum (CCe) of the losers while modestly higher expressions were also detected in the dorsal habenula, IPN and griseum centrale (GC) of the losers than the winners. Our findings revealed the differential neural status between winner and loser by egr1 mRNA expression. Nevertheless, it also implied the involvement of vHb and its downstream circuit in loser determination.