Of course fish can count. In fact, our aquatic compatriots can hold their own in numbers games just about as well as a sampling of college undergraduates. "According to a new study, college students showed roughly the same numerical skills as the small fish when presented with a laboratory test," writes Matt Kaplan for National Geographic.

Practically speaking, the research team behind the new study doesn't appear to be comparing the math prowess of fish and humans as much as trying to find patterns and similarities between the species' cognitive abilities. To do so they constructed a series of tests constructed to test the numerical skills of fish--mosquitofish to be exact--by having them swim between "identical doors bearing different numbers of symbols" with a path to rejoining a larger group:

The fish were then placed in tanks where they had to chose between one of two identical doors bearing different numbers of symbols. For example, four shapes might be associated with door A and eight shapes with door B. At the beginning of the test, the fish did not know where to go, and they chose randomly. Over time, however, the fish started to chose the correct door more often than by chance alone.
Researchers then rounded up a group of 25 undergraduates to engage in a test that "presented them with the same types of challenges" (i.e. determining the differences between larger numbers very quickly). It turns out both fish and humans can distinguish large differences fairly easily. It's when the ratio becomes something like 3:4 instead of 1:2 or 2:3 that both groups start to have difficulty. The verdict? Fish seem to think in a similar way as humans. According to head researcher Christian Agrillo "the results add to evidence that humans, fish, and other vertebrates share the same abilities for processing numbers as a distant but common ancestor," notes Kaplan.