Data included are DNA sequences used to identify species boundaries among Ichthyophonus-like parasites. Sequences were generated for three gene regions from each parasite isolate. DNA sequences can be downloaded from GenBank (https://www.ncbi.nlm.nih.gov/) as text or fasta files. Accession numbers for each sequence are included in the data table (.csv file). Data includes 87 sequences (99,383 total nucleotides). Once manuscript is accepted there are no restrictions on dissemination of these data.