SRP326817 PRJNA743555 Capped-small RNA-sequencing (csRNA-seq) of populations of poeciliid fish from hydrogen-sulfide rich and non-sulfidic springs in Mexico We performed capped-small RNA-sequencing (csRNA-seq) on 12 individuals of Poecilia spp. sampled from both sulfidic and non-sulfidic springs in southern Mexico (3 non-sulfidic populations, 3 sulfidic populations, 2 individuals from each site). csRNA-seq captures short (~20-60 nucleotides) stable and unstable RNA transcripts. Each fish sample has a "csRNA" file that contains the sequences of only 5' capped small RNAs and an "input" file that contains total RNA sequences as a way to eliminate false positives. See Duttke et al. 2019 "Identification and dynamic quantification of regulatory elements using total RNA" in Genome Research for a full description of csRNA-seq.