Triploid ZZZ Z ebra F inches T aeniopygia guttata exhibit abnormal sperm heads and poor reproductive performance

Here we report the first discovery of two viable triploid male Z ebra F inches T aeniopygia guttata . We compared the morphology of their sperm with that of normal diploid Z ebra F inches and examined eggs resulting from a triploid male and diploid female pairing to investigate whether triploid Z ebra F inches can reproduce. The majority (78%) of the triploids' spermatozoa had malformed sperm heads, which were 60% larger, and all examined eggs ( n  =   42) were infertile. Our results tentatively suggest that triploid ZZZ Z ebra F inches cannot reproduce, and thus represent a rare evolutionary dead‐end.