Comparison of three microquantity techniques for measuring total lipids in fish

To measure lipids in juvenile and adult fishes, we refined three microquantity approaches (microgravimetric, microcolorimetric sulfophosphovanillan (SPV), and Iatroscan thin layer chromatography - flame ionization detection (TLC-FID)) that were originally developed to measure lipids in small aquatic invertebrates. We also evaluated their precision and comparability by quantifying the total lipid content of age-1+ walleye (Sander vitreus), yellow perch (Perca flavescens), and lake whitefish (Coregonus clupeaformis) collected in Lake Erie (US-Canada), Lake Michigan (USA), and Muskegon Lake (Michigan, USA). Our findings demonstrate that (i) microquantity approaches provide estimates of total lipids in juvenile and adult fishes similar to those of more traditional macroquantity approaches, (ii) the microcolorimetric SPV and microgravimetric approaches produce near identical estimates of total lipid content, and (iii) the Iatroscan TLC-FID approach underestimates total lipids relative to the other approaches for individuals with high lipid levels. Ultimately, our research makes available additional techniques for measuring total lipid content of fishes that are less expensive than traditional techniques, owing to a reduced need for large quantities of samples and solvents.