Giant Sewer Rat

The Giant Sewer Rat is a rat companion pet. True to its name, it is considerably larger than other rats.

Source
This item is rarely fished up from the Underbelly in Dalaran.

It can also randomly drop from any loot container that is from a boss.

It can also be listed on the Black Market Auction House by Breanni, for the opening bid of.

Pet Journal
''You wouldn't want to meet this rat in a dark alley. Or anywhere else, for that matter.''

Required for
The player must fish this up to earn the I Smell A Giant Rat fishing achievement.