GRAPHIC VIDEO: A pervert was arrested for allegedly having sex with his neighbour's koi fish.

Sex-starved Sutthichai Boonlert, 51, reportedly scooped the hapless koi fish from resident Bobby Anong's pond before using its mouth to pleasure himself.

CCTV captured the shocking sex act as the senior citizen took off his clothes and entered the water in a quiet neighbourhood in Bangkok, Thailand, on September 7.

He held a white dildo while rubbing the koi fish on his genitals before emerging from the pond. He was then seen walking to a dark corner before appearing to use the flailing animal as a makeshift sex toy.