Today’s facts may be tomorrow’s fallacies. And last Thursday, I got a serious reminder that science is a progressive continuum of new discoveries, and not a static body of facts.

I study minnows, and last year I wrote a post to clear up some misconceptions about minnows. Things like how many small fishes are called ‘minnows’, but indeed are not. And how carps are often mistaken for suckers, but are actually minnows.

And how native North American minnows are members of the family Cyprinidae.

But now they’re not.

Published just last week, a study by Tan and Armbruster in the journal Zootaxa presented a revised grouping of the Cypriniformes—the most diverse order of freshwater fishes in the world. And what an undertaking it must have been—there are over 4,000 species to sort out!

They concluded that Cyprinidae, in the broad sense, was too big of an umbrella to group all those species together in one family. Instead, what we learned in Ichthyology as Cyprinidae actually represents something broader than a family, and that group contains several families. The ‘new’ Cyprinidae, in a strict sense, has been refined to include much fewer genera.

So, most of the minnows native to North America are now considered to be members of the family Leuciscidae.

This represents an important lesson for all of us, but especially students. Our knowledge of relationships among organisms represent hypotheses that are testable and subject to scrutiny and refute.

As new tools develop and new evidence emerges, our understanding of relationships, and even species themselves, must be revised. Even in the US, where ichthyologists have been working for over two centuries, we’re constantly discovering new species.

And with it go scientific names. I joke with my students, ‘when I was your age, Chrosomus was Phoxinus, there were only a few black bass species, and Pluto was a planet’.

This all goes to provide perspective on how we operate as biologists. Just because we learned something in school doesn’t mean it’s infallible and permanent. We do our best work, accept when it’s wrong, and try to move science forward a step or two.