Hundreds of dead fish are floating in a pond at Angrignon Park, leaving some residents wondering what is causing them to turn belly up.

A resident noticed the fish when he was walking along the kilometre-long pond in the South West borough's park on Monday.

He said he called the City of Montreal and was told someone would come take a look at the hundreds of dead minnows and other fish.

The few fish that are still alive seem to be quite fragile.

Concordia biology professor Jim Grant said there isn't much anyone can do to save them.

"The likely cause is probably a lack of oxygen. We've had a severe winter. Ice cover means no oxygen getting in from the air. The wind can't mix the water, so oxygen levels aren't going up," he said.

He said these conditions don't happen every winter and he expects the fish population to bounce back in the spring.

A city inspector is supposed to come see the fish over the weekend.