Montreal researchers wanting to see how our ancestors evolved raised fish that can walk on land to show how being out of water changed the way the fish looked and moved.

The McGill University researchers raised a fish called a Polypterus, which can breathe air, walk on land using their front fins, and looks like ancient fishes that evolved into tetrapods - four-limbed vertebrates.

The "terrestrialized" fish - meaning they were raised out of water - showed significant anatomical and behavioural changes, the researchers said in the study, published this week in the journal Nature.

The fish raised on land walked more effectively, lifted their heads higher and kept their fins from slipping more than the fish raised in water.

"Anatomically, their pectoral skeleton changed to become more elongate with stronger attachments across their chest, possibly to increase support during walking, and a reduced contact with the skull to potentially allow greater head/neck motion," researcher Trina Du said in a release.