ATHENS, Ohio – There's hope for the less-than-perfect male – if you're a swordtail fish, that is. As the size and age of female swordtail fish increase, so does the preference for males with ...

Swordtails are well-known beginner-friendly, community fish species, compatible with various other fish and environments. They have been bred for many generations, resulting in many different ...

Justin Havird, Erik Iverson and their colleagues have identified genes involved in hybrid incompatibility in swordtail fishes. The sheepshead swordtail fish (Xiphophorus birchmanni). Photo credit: Dan ...

There are more than 34,000 species of fish on our planet. It can be tricky to tell the age or gender of a fish, but biologists have come up with a few different ways to find out. My friend Paul ...