A small Alaskan rainbow trout was found with almost 20 shrews in its stomach.

Researchers examined the body of the trout, found in Alaska's Togiak National Wildlife Refuge. Once the trout's body was opened up, researchers discovered that the trout had eaten almost 20 different specimens of the mouse-sized mammal.

That was "an awful lot for one fish to put down," Mark Lisac, a fish biologist at Togiak National Widlife Reguge in Alaska, said in an interview with LiveScience.

The record for a trout eating shrews was previously set at seven. The record was held by a grayling, a type of fish that "keys in on shrews even more" than rainbow trouts, Lisac said.

At 19 inches long, Lisac said that the trout is considered small. As a result, scientists wondered how the fish could have eaten so many shrews.

Part of the phenomena could be due to the fact that shrews are poor swimmers and often drown once they enter a body of water.

"My best guess is that the shrews were on an island [or river bank] that flooded, and the rainbow happened to be in the right spot at the right time," Lisac said.

Rainbow trouts eat a lot in the summer in order to prepare for winter, a season where the fish does not eat or move very much. Fish related to the rainbow trout enlarge their digestive tracts in the summer and then digest the excess intestine in the winter. Rainbow trout may also perform this feat, according to Lisac.

"Top predators, like trout, have large distensible stomachs that allow them to consume large prey items or a lot of smaller items," Trent Sutton, a fisheries biologist at the University of Alaska Fairbanks, said. "I do not know why there would be a lot of shrews where a trout could access them..."

Rainbow trout, and other species of fish related to the rainbow trout, are known to eat shrews as well as other small mammals such as rodents. Various freshwater fish species are "opportunistic feeders" and prey on myriad species.

Insects, smaller fish and salmon eggs are common foods in the rainbow trout's diet. They also eat voles and other rodents.

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