The fisher (Martes pennanti) is a small carnivorous mammal native to North America. It is a member of the mustelid family (commonly referred to as the weasel family) and a part of the marten genus. The fisher is closely related to but larger than the American marten (Martes americana). The fisher is a forest-dwelling creature whose range covers much of the boreal forest in Canada to the northern United States. Names derived from aboriginal languages include pekan, pequam, wejack, and woolang. It is also called a fisher cat, although it is not a feline.
A fisher first appeared at the beginning of the very first episode "The Nose Knows", making it the very first animal to appear in the series. It was in Animal Junction when the Kratt Brothers entered from the bat cave.
Another fisher appeared in "Tracks". When Chris and Martin found mustelid tracks along with Jackie's, a fisher was the last mustelid they thought to have made the tracks. When they found Jackie, she told them that a fisher chased a porcupine up the tree she was in, proving that a fisher indeed made the mustelid tracks. They all spotted both the porcupine and the fisher in the tree. Martin stated that when there's snow on the ground, a fisher can jump 20 feet out of a tree. Jackie then watched the fisher as it climbed down the tree to the snowy ground and complimented on how it did. Chris also added that in the winter, fishers travel huge distances across the snow, looking for food, and that a porcupine are their favorite meal. Martin reassures that a porcupine's safe as long as he has his quills and can climb up in a tree.
A fisher also appeared in "Stinky" along with several other mustelids.