Among the fish populations that could be harmed by the Xayaburi dam in Laos is the critically endangered Mekong giant catfish, considered by the Guinness Book of World Records to be the world’s largest freshwater fish. The fish, which grows to 650 pounds and about 10 feet long, is only found in the Mekong River. It is migratory, moving between downstream habitats in Cambodia upstream to northern Thailand and Laos each year to spawn. Some experts fear the Xayaburi dam could block the migration and drive the giant catfish to extinction. (Photo by Courtesy of Zeb Hogan/University of Nevada, Reno)

Kevin Fast, 51, holds several Guinness World Records including the heaviest plane pulled by a man and has lifted 22 women with his back. The Reverend Dr Kevin Fast is officially God's gift to powerlifting after being named as the world's strongest priest. The Canadian pastor, 51, has been performing incredible stunts of heavy lifting for years after being inspired by 19th Century strongman Louis Cyr. He holds several Guinness World Records including the heaviest aircraft pulled by a man, which weighed in at a whopping 189 tonnes, heaviest truck pulled by an arm wrestling move, heaviest vehicle pulled over 100ft and the longest duration holding 500kg with the shoulders.

Garry Stretch, who holds the Guinness World Record for having the stretchiest skin performs before he judges the auditions for the Circus of Horrors at Fairfield Halls on October 7, 2005 in London, England. Hundreds of people applied for a job in the circus after advertisments were placed in many of London's job centres. (Photo by Scott Barbour/Getty Images)

Revellers take part in a Zombie Walk in Asbury Park, New Jersey October 4, 2014. Thousands of revellers met in Asbury park to attempt to break the Guinness World Record of the largest zombie gathering in the world and raise awareness for brain cancer. (Photo by Eduardo Munoz/Reuters)

The World’s Smallest Horse according to Guinness World Records is Thumbelina from Missouri, but another tiny horse named Einstein.

A soldier poses with a Hythe Mk III Gun Camera during training activities at Ellington Field, Houston, Texas in April of 1918. The Mk III, built to match the size, handling, and weight of a Lewis Gun, was used to train aerial gunners, recording a photograph when the trigger was pulled, for later review, when an instructor could coach trainees on better aiming strategies. (Photo by Harry Kidd/WWI Army Signal Corps Photograph Collection via The Atlantic)