Many ancient fish actually favored the cold, dark, barren waters of the deep sea instead of the shallow warm ocean full of resources.

Findings with stickleback fish counter a key assertion by anti-evolutionists and offer support for the concept of progressive evolution.

Scientists have debated whether the evolution of teeth occurred outside-in or inside-out. Sawfish fossils may hold the answer.

Researchers pulled a coelacanth caught in 1960 from its jar of alcohol in a museum and gave it an MRI. Doing so reveals some of the fish's mysterious ways.

The megalodon was an even more fearsome predator than previously thought, able to take down prey the size of modern orcas.

Research shows that coral reefs' diversity of fish results from a relatively recent innovation among bony fish: biting prey from surfaces.

Forming large groups while in the ocean protects Pacific salmon from predators, research finds. It can also limit how much they eat.

Hanging out with other guppies can offer protection against predators, but all that social mingling can set them up for breeding deadly parasites.

A new study finds a connection between eating fish and developing skin cancer. Researchers say bio-contaminants like mercury are a likely cause.

Guppies and mosquitofish can turn to cannibalism in your fish tank, but it's rare to find them eating their other members of their own species in the wild.