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© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in BMC Genomics 16 (2015): 243, doi:10.1186/s12864-015-1288-8., With its unique ability to produce high-voltage electric discharges in excess of 600 volts, the South American strong voltage electric eel (Electrophorus electricus) has played an important role in the history of science. Remarkably little is understood about the molecular nature of its electric organs. We present an in-depth analysis of the genome of E. electricus, including the transcriptomes of eight mature tissues: brain, spinal cord, kidney, heart, skeletal muscle, Sachs’ electric organ, main electric organ, and Hunter’s electric organ. A gene set enrichment analysis based on gene ontology reveals enriched functions in all three electric organs related to transmembrane transport, androgen binding, and signaling. This study also represents the first analysis of miRNA in electric fish. It identified a number of miRNAs displaying electric organ-specific expression patterns, including one novel miRNA highly over-expressed in all three electric organs of E. electricus. All three electric organ tissues also express three conserved miRNAs that have been reported to inhibit muscle development in mammals, suggesting that miRNA-dependent regulation of gene expression might play an important role in specifying an electric organ identity from its muscle precursor. These miRNA data were supported using another complete miRNA profile from muscle and electric organ tissues of a second gymnotiform species. Our work on the E. electricus genome and eight tissue-specific gene expression profiles will greatly facilitate future research on determining the coding and regulatory sequences that specify the function, development, and evolution of electric organs. Moreover, these data and future studies will be informed by the first comprehensive analysis of miRNA expression in an electric fish presented here., This project has been funded in part by NSF Grant MCB No. 1144012 (MRS), NSF Grant DEB No. 0741450 (JSA), NSF Grant CNS No. 1248109 (GAU), W.M. Keck Foundation Distinguished Young Scholars in Medical Research (CDN), NIH R01 GM084879 (HZ), NIH grant R01 GM088670 (RA), NIH grant 1SC1GM092297-01A1 (GAU), the Morgridge Graduate Fellowship (JDV and LLT), University of Wisconsin Genetics NIH Graduate Training Grant (LLT); and the Cornell University Center for Vertebrate Genomics (JRG).