design: Fish from the Rabbit Slough (RABS) and Matanuska Lake (MLK) populations were crossed.  At 1, 3, 4, and 5 days post hatching, a set of fish were used to isolate brain tissue. RNA was extracted using  Direct-zol RNA Miniprep Plus kit. Illumina TruSeq Stranded mRNA library prep kit was used for RNA-seq library.