The goal of this study was to develop a simple, cost effective method to mark fish through oral delivery of an indicator that could be qualitatively and quantitively assessed based on consumption. Our objectives were to 1) determine the concentration of orally administered Sudan Black B required for qualitative confirmation of ingestion, 2) trace the biodistribution of Sudan Black B in several fish tissues, and 3) quantify feed consumption by extracting orally delivered Sudan Black B from several tissues. Additionally, the time required to detect Sudan Black B in each tissue, effects between species, and optimal tissues for Sudan Black B extraction were determined. Methods were developed to quantify absorbance of Sudan Black B extracted from multiple fish tissues using a spectrophotometer. The dataset includes raw files for time-till-blue, biodistribution, feeding, and a case study for three freshwater fish species. Each file includes species information, observational data, treatment information of Sudan Black B, and absorbance estimates from tissue extractions.