The first transcriptome of the diaphanous deep-sea hatchetfish Sternoptyx diaphana Hermann, 1781 (Teleostei:...

Marine hatchetfish (Stomiiformes: Sternoptychidae) are among the most abundant and diverse inhabitants of the mesopelagic zone. Despite their small size, they have a high global biomass and play a crucial ecological role. These fish exhibit a distinctive morphology, characterized by highly compressed, silvery bodies and intricate bioluminescent organs known as photophores, which enable light production. The photophores of marine hatchetfish are among the most complex known bioluminescent structures; yet, their functional molecular components remain poorly understood. This knowledge gap is further exacerbated by the scarcity of genomic resources available for the group. Genomic tools such as RNA sequencing (RNA-seq) are crucial for uncovering the molecular mechanisms underlying their unique traits. Here, we present the first transcriptome assembly of a marine hatchetfish, the diaphanous hatchetfish Sternoptyx diaphana Hermann, 1781, based on a multi-tissue RNA-seq approach, including brain, heart, muscle and photophores.