Man Arrested For Having Sex With Koi Fish In Disgusting Video

There's apparently not enough fish in the sea ... a man in Thailand was caught on camera stripping down to have sex with a koi fish ... and he was arrested after putting the poor animal's mouth on his penis.

Disturbing CCTV footage shows the moment a naked man hops into a koi pond, grabs a fish, and uses the swimmer to pleasure himself.

We won't show you the whole sex act ... it's too graphic for our taste ... but you get the idea from the clip.

The man was reportedly identified as 51-year-old Sutthichai Boonlert ... and the koi fish belonged to his neighbor, Bobby Anong. Cops say Boonlert initially claimed he got in the pond to wash off and became aroused when the fish swam near his penis.

This all played out Monday in Bangkok ... and local police say this isn't the first time the guy has turned animals into sex toys ... including a pregnant dog.

Unsurprisingly, cops say the man told them he doesn't have a girlfriend ... and he's too broke to hire one of Bangkok's infamous sex workers.