WATCH: Fish 'beauty pageant' in Singapore

The brightly coloured Siamese fighting fish glared at one another from inside adjacent glass jars, flaring long, wavy fins and tensing up as if to pounce, during a tournament in Singapore. 

Many in Asia have long enjoyed keeping the tiny fish, which are highly territorial and so aggressive that putting two males together in a tank inevitably leads to a clash, which is often fatal. 

They are native to Thailand, and the most beautiful can fetch huge sums at auction.

Last year one of the creatures sporting the red, white and blue stripes of the Thai flag sold for 53,500 baht (S$2,190). 

Public fights are sometimes still staged despite attempts to curb the practice but many owners prefer to take them to beauty pageant-style shows, where they are not harmed, such as the recent one in Singapore. 

At the tournament, collectors of the fish - which typically grow to only 6.5 centimetres (2.5 inches) - got the chance to showcase about 600 of them from countries including China, Indonesia, the Philippines and Taiwan. 

"I like the fighting fish because of its aggressiveness. When it flares its fins, it's so beautiful," said Chan Kean Yap, 28, owner of the show's grand champion. 

They were placed in glass jars next to one another, and judges observed them for their fighting posture, as well as size and vibrancy of their colours. 

They were grouped into different divisions, according to their finnage, colour and size, with a winner picked from each division and a grand champion selected from among those victors.