LiveLeak description:

It was originally built as an 11-story building, which violated local zoning codes allowing for only four stories.

The top seven floors were demolished to adhere to the codes, and two years later there was a fire that further damaged the building. The remains have no roof, which keeps them in a perpetual state of flooding.

A mosquito problem eventually developed in the standing water, and locals introduced freshwater tilapia in the water to eat the mosquitos. The fish population soon took over the lower floors of the watery space, swimming around rusted escalators and other remnants. Visitors and locals, who feed the fish with fish food supplied by area stores for that purpose, have since added other types of exotic fish, such as Koi carp, to the mall mix.

More info here: http://www.vintageasian.com/759-floating-market/

There are also some photos in the LL article, http://www.liveleak.com/view?i=651_1404126690