The proposed and ongoing Fish-T1K project will be an invaluable resource for all research fields that are concerned with fish, including even pharmacology and translational medicine. A particular strength of the proposed strategy is the comparability of the obtained sequence data sets as stringent standards for sample acquisition and data generation are well developed. The present commentary, which publicly introduces the Fish-T1K project, is well written and I have only a few minor comments for some further improvement below. I am looking forward to further updates on this milestone project!

Figures 2, S1: I would prefer if the fish orders were represented in form of a phylogenetic tree. Of course, one of the major future goals of the present study is to update our understanding of fish phylogeny, but organizing the numbers phylogenetically here instead of a pie chart would help to better orient the reader. All relevant numbers such as extant species; species collected; already sequenced by the project; and already in the SRA database (Fig. S1) could be reported here in one figure next to a phylogeny.

p.4, l.71: One could add: "…, and as evolutionary models for specific human diseases and conditions [e.g. Albertson et al. 2009, Trends Genet; Schartl 2014, Dis Model Mech]."

p.4, l.78-80: Better say: "…applied to model fish species like zebrafish... and medaka… and multiple non-model fish species"

p.5, l.5, l.92: Please add 'ray-finned': "… transcriptomes of 1,000 different species of ray-finned fishes"

SOPs and best practices (p.8): It would be good to give some explanation why these specific tissues have been selected for tissue collection and also why gills are the preferred tissue for RNA extraction. Is it expected that gills are particularly comparable or diverse in terms of gene expression? Is a particular age category and sex preferred for fish samplin?

Current progress of RNA sequencing (p.9): It would be nice to provide a supplementary table with the 136 species already sampled.

Figure S2: The color code is a little difficult to understand, please provide additional info in the legend.

Table S1: Common names should be provided as well. As the field is so much in flux, this table and relevant numbers in the text should be updated at the time of publication.

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