The fish will be kept there for about three weeks before being released to reservoirs, canals and rivers, said Veera Watcharagoneyotine, director of the centre in Samut Prakan, while supervising Tuesday's project.
''There are about 3,000 fish, most of them mango fish, striped catfish and catfish,'' he added.
The pond attracted public attention in June last year when photos of it were posted online, drawing more people to visit the abandoned centre to feed them. The district office later declared the building off limits due to safety concerns.
In fact, the Bangkok Metropolitan Administration had barred entry to the premises since 2011, but the public ignored the order.
The history of the pond dates back to 1997 when the Supreme Court ordered the demolition of the seven-storey extension of the 11-storey shopping centre. The judges uncovered the fact that the store operators originally asked for permission from City Hall to construct a four-storey building.
The seven floors illegally added to New World were then demolished by the BMA. The work left a four-storey structure, with no roof or covering. Years of rain turned the waterlogged ground floor into a 500sqm pond.