This is the bizarre moment hundreds of fish swam together forming a strange ball in the shallow part of a sea in eastern Thailand.
Footage shows the striped eel catfish swimming closely to form the ball in Koh Chang, Trat province on April 12.
Amazed tourist Ratchanon Winlawat said: ‘I found something like a black ball around the shore while walking during my vacation trip.
‘When I went to take a look at it closely I saw the group of lagoon catfish forming like a ball. I had never seen anything like it before.’