Skin permeability of Sevan trout has been studied during 30 min in different solutions: in distilled water, in 70% ethanol, in solution of 0.125 M KCl. The permeability was measured by methylene blue. It was shown that the skin permeability for this dye changes depending, on what solution these shreds of Sevan trout were kept and what side the shred was tightened from. It was also shown that distilled water, solution of 0.125 M KCl and ethanol result in structural changes of Sevan trout skin layers, particularly epidermis.