Environmental officials in Vietnam are sounding alarms over the new fad of breeding piranhas in the Mekong Delta, saying the flesh-eating fish could spell ecological disaster if they escape into rivers during the next flood season.

"What we now fear most is with the flooding season coming is that these fish may get out of the ponds and into the rivers," said Pham Huu Khanh, head of Cat Tien National Park's department of science and technology.

"With their astonishing survival ability and breeding rate they would multiply and kill many, if not all, other species in the rivers," Khanh said Monday.

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