Travel website world famous Lonely Planet has just published a list of 10 interesting fishing locations in the world in 2015, including Vietnam's Ha Long Bay ranks 9th. 

The lonelyplanet has an introduction to fishing on the bay as follows:

Fishing experience on Halong overnight cruises

The word ‘squid’ mightn’t conjure up the warm-and-fuzzies right now, but after a night on Halong Bay, that will change. Dozens of junks ply the bay’s jade-green waters on moonless evenings, fishing for the slippery little cephalopods that go into the region’s best-known speciality: squid sausages. With only a bamboo rod, a catch net and a lamp to attract the squid to the surface, anyone can hook themselves an impressive 30-plus squid in just a couple of hours. The stillness of the bay dotted by the dreamy reflection of the lamps makes for a contemplative, romantic evening.

Squid season in Halong begins in April and runs through until January: the biggest squid are caught between October and November.

Book yourself an Halong overnight tour for an exciting fishing experience on Halong Bay