Radiation protection has historically been from a human protection approach, therefore many studies have neglected the potential dose contribution from the gastrointestinal tract (GIT) in animal studies. The International Commission on Radiological Protection (ICRP) utilized simplified geometric shapes with Dose Conversion Factors (DCF) based on homogenized models for the trout reference animal, one of twelve reference animals and plants (RAPs). Utilizing data collected from Pacific Proving Ground site studies from the 1960's-1970's, dose rates estimations were done, with and without the contribution of the GIT, using activity concentrations of ²³⁹ ²⁴⁰Pu, ⁹⁰Sr, and ¹³⁷Cs in tissues of fish from varying trophic levels. The comparison of voxelized models with ICRP 108 DCFs and homogenized whole body dose method were also compared. Dose rate estimations excluding the GIT resulted in an underestimate of dose rate by more than a magnitude in some cases. Individual organ dose rates calculated using the voxel models to whole body dose rates calculated using the homogeneous model dose rates differed by a magnitude of -1 to 4.