Killifish manage to endure a variety of environments. The wee freshwater fish survive in isolated desert pools, lakes made by flood water, even seasonal ponds that are little more than puddles.
One place scientists didn’t expect to find them was in swan poop. But an international team of researchers reported last week in the journal Ecology that whole killifish eggs make it through the digestive tract of water birds intact, with one egg in the study even hatching more than a month after its transit through a swan. The findings suggest that bird feces may be capable of carrying fish eggs far from their original locations. [...] The researchers are planning a similar experiment now that uses eggs from carp, which hatch much faster than killifish. As killifish and carp can be invasive species outside of their normal range, understanding how they spread can help in containment.