kcnk10a has been predicted in zebrafish to be a member of the two-pore domain potassium ion (K+) channel-related K+ (TREK) channel family known as a thermoreceptor. Since reproduction is affected by temperature, Kcnk10a could be involved in the regulation of reproduction. However, expression of kcnk10a in the zebrafish brain and association with reproduction has not been identified. In this study, the full length sequence and localization of kcnk10a in the brain was investigated and gene expressions of the TREK channel family were examined to investigate association with reproduction. We initially identified the full length cDNA sequence of kcnk10a using Rapid Amplification of cDNA Ends and localization in the zebrafish brain using in situ hybridization. Furthermore, we examined the gene expression differences of kcnk2b, kcnk10a and kcnk10b mRNA between genders as well as developmental stages by real-time PCR. The deduced amino acid sequence of the identified kcnk10a mRNA contains highly conserved two pore domains and four transmembrane regions and was higher similarity to zebrafish Kcnk10b than zebrafish Kcnk2a and 2b. kcnk10a mRNA was widely distributed in the brain such as the preoptic area, hypothalamus and the midbrain. kcnk10a mRNA expression exhibited significant difference between mature male and female, and increase during puberty. Kcnk10a could be involved in the regulation of reproductive function.