Natural Occurrence of Triploidy in a Wild Brown Bullhead

We report the rare, natural occurrence of triploidy in a brown bullhead Ameiurus (formerly Ictalurus) nebulosus. This is to our knowledge the first report of naturally occurring triploidy within the family Ictaluridae. The nuclei of blood cells were studied by flow cytometry, volume measurement, and computer-assisted image analysis. The triploid had a genome size of 3.29 pg DNA/cell compared to 2.23 pg DNA/cell (SD, 0.02 pg) for 28 diploid brown bullheads. Volume measurement and image analysis were able to detect the triploid condition; however, flow cytometry was the most precise technique and had the greatest resolution.