PHUKET: Fisherman have been catching unusually large longtail tuna in the waters south of Phuket recently, experts say.

One of the fish, so large it was originally thought to be a "little tunny" or "false albacore", was brought for examination to the Andaman Sea Fisheries Management Center Krabi on Tuesday.

The specimen, weighing in at 5kg, is a good sign for the condition of the water off the coast of Krabi, said center director Jaroen Omane.