Threatened and endangered species were among the dead, likely poisoned overnight by a chlorination system used to decontaminate the animals’ tank water.

The fish species is separated from mammals by hundreds of millions of years of evolution, yet its seemingly primitive brain can handle many of the same elaborate visual tasks.

The roar of nearby boat engines alters how fish care for and protect their young, resulting in fewer successful nests and smaller offspring, a study finds.

Once thought to be silent, fish turn out to produce a range of vocalizations—so polluting the oceans with noise could pose a danger to them.

The Scientist spoke with cognitive neuroscientist Ronen Segev about how he taught goldfish to maneuver a moveable tank over land toward a visual target.

Moving collectively on the water surface could help protect schools of fish from being eaten by predatory birds.

An analysis suggests that a commercially important mass migration of fish may have no real adaptive value.

A study of feeding behavior suggests the fish feed differently in front of their partners—a behavioral feature also found in primates.

Researchers discover surprisingly high levels of genetic diversity among the colorful male morphs of a freshwater fish.

Bettas were likely the first fish welcomed into human homes. Now, scientists are welcoming them into the lab to learn how genes dictate their appearance and behavior.

After eight weeks of exposure to ecologically plausible levels of methamphetamines, the fish tended to prefer meth-laced water over water without the drug.

The new experiments use standardized methods and video recordings, but some researchers stand by earlier evidence that ocean pH influences coral reef fish’s response to predator cues.

The Penn State University scientist was known for her work on fish’s perception of pain.

The bioluminescent Anomalops katoptron can coordinate its schooling behavior after dark. 

A fossil of a school of fish from the Eocene appears to represent coordinated collective movement.

Watch a Munk’s devil ray breach.

Nearly 50 years after its development, only a handful of creatures have passed the self-awareness exam. A new attempt with fish highlights a debate over the test’s use and meaning.

From cellular self-digestion to the effects of exercise on the brain, our features editor picks her favorite art custom-made for the magazine.

Digesting a big meal takes energy, forcing some minnows to swim in spots at the rear of a school.