Warmer than usual weather has been affecting native flora and fauna but it has also brought some unusual marine visitors to Nova Scotia waters.

A school of several grey triggerfish, usually a tropical species, is giving Nova Scotia divers a unique view.

Bob Semple, a local diver, has been watching the southern visitors.

"I heard this big 'crunch' and it went down and it got a green crab, and it ate a green crab," he said, "Probably not their typical food."

The small fish, usually less than 2.3 kilograms, is commonly found throughout the warmer parts of the western Atlantic Ocean.

Triggerfish are occasionally found off the coast of Nova Scotia but usually in late summer to early fall when the water is warmest. (Still from Bob Semple's video)

Identifying characteristics of the species include tough, leather-like skin, and iridescent blue patches along its body.

Grey triggerfish are not the only tropical aquatic visitors, flying fish were spotted in the waters around Halifax harbour last week.

Last August a 180-kilogram tropical sunfish washed up during low tide in Annapolis County.

At the Nova Scotia Museum, Zoology Curator Andrew Hebda says it is not unusual for warm water fish to hitch a ride on the Gulf Stream to Canada.

Triggerfish are occasionally found off the coast of Nova Scotia but usually in late summer to early fall when the water is warmest.

Hebda has been tracking all the unique arrivals.

"We're about two weeks ahead of what we normally see, which would mean, if it stays warm in the fall, we'll see more fish than we normally do," says Hebda.

While some of the fish may be able to find their way back to warmer waters, others won't survive the winter.

Hebda says it's possible for tropical marine species to become permanent fixtures off the coast of Nova Scotia.