In this work, three species of troglobitic fish (Ituglanis passensis, Trichomycterus itacarambiensis and Stygichthys typhlops), each found in a different region of Brazil were tested. Brazil has a high abundance of caves, but most of them have not been discovered or biologically explored. Consequently, the fauna associated with cave environments are threatened by ignorance towards their potential extinction of the fauna. With the intention of preserving the species and environments associated with them, the lipid composition of each fish was studied to determine the influence of the subterranean environment on the metabolism of these animals, especially those that were altered due to the medium they inhabited. Gas chromatography with flame ionization was used to analyze and identify the fatty acids in each species; experiments showed 25 fatty acids in Ituglanis passensis, 28 in Trichomycterus itacarambiensis and 25 in Stygichthys typhlops. Some of the acids were present in higher concentrations in relation to others for all species; these were palmitic (C16:0), stearic (C18:0), oleic (C18:1 ω9c), and linoleic (C18:2 ω6c) acids. Results demonstrated that the lipidic compositions of each analyzed species were influenced by conditions of their habitat; mainly feeding.