This folder contains the data file for the article: Esin, E. V., Markevich, G. N., Melnik, N. O., Kapitanova, D. A. and F. N. Shkil (2021). Natural toxic impact and thyroid signaling interplay orchestrates riverine adaptive divergence of salmonid fish. Journal of Animal Ecology We investigated how thyroid signaling can control a diverse range of outcomes, various adaptive phenotypic novelties and riverine sympatric divergence. Our results along with the data concerning thyroid involvement in the diversification of various fish groups indicate that thyroid axis orchestrates the subtle phenotypic plasticity in fish promoting evolutionary diversification under shifting environmental conditions. Comments and requests should be addressed to Evgeny Esin: evgesin@gmail.com. All material is free of use, but I would appreciate this dataset and the matching paper cited if appropriate. The file named JAE_Esin_etal_2021(.XLS format)contains source data sets for the final version of the manuscript. The file is divided into five sheets containing different independent data blocks: Sheet 1 contains the data on full length (in mm) and total weight (in g; mean values at the end of columns are marked red) of all experimental fish groups including common-garden experiment and thyroid alteration experiment. The data was used in fig. 2. Sheet 2 contains the data on the total thyroid (T3) concentrations (in ng / g) in the extract of a whole fish from the common-garden experiment, thyroid alteration experiment and the experiment with the conifer infusion impact. All experimental groups and its age in day*degrees are marked. The hormone concentrations were evaluated by enzyme-linked immunosorbent assay (ELISA) barbital-free procedure adapted from Schnitzler et al. (2008, doi: 10.1016/j.marpolbul.2008.06.011). The data was used in fig. 1. Sheet 3 contains the data on three physiological parameters (i.e. glucose concentration in the blood (in mmol/L), antioxydant activity of tissues (in mU/L) and phospholipid concentration in the muscles (in g/L)) of the experimental fish. All experimental groups and its age in day*degrees are marked. The data was used in fig. 3. Sheet 4 contains the data on the ossification ranks of several cranial bones: supraethmoid (set), frontal (fro), parasphenoid (phsp) and orbital series (orbita) bones; premaxilla (pmx), maxilla (mxl), dentary (den), and vomer (vom); alveolar teeth formulae on palatine (pal) and lingual bones (glo), the number of ossified sections (osb) and rakers (sb) of the first gill arch. All experimental groups and its age in day*degrees are marked. Mean values of the ranks are marked red. The data was used in fig. 5. Sheet 5 contains the data on the linear morphometric measurements (in pixels) of fish from the common-garden experiment and thyroid alteration experiment. All experimental groups and its age in day*degrees are marked. The data complements fig, 4, b and ñ.