In Bangkok’s historic center, an abandoned department store turned into a shimmering, rain-fed aquarium—an improvised answer to a very modern city problem: mosquitoes.
How a shopping mall became a pond
For years, the concrete shell of the New World Department Store loomed over the old quarter, its escalators frozen mid-climb and shop bays long stripped bare. After construction disputes in the late 1990s led to partial demolition, the building lost much of its roof. Bangkok’s monsoon did the rest. Rainwater pooled and kept pooling, eventually filling the lower levels into a deep, shadowy basin.
Standing water in a tropical capital is more than a curiosity. It’s a breeding ground for mosquitoes, with the Aedes species thriving in clean, stagnant pools. As months turned to years, locals living and working near the derelict store faced the familiar buzz of an old enemy, one tied to dengue fever outbreaks that strike Thailand by the tens of thousands in peak years.
A neighborhood’s improvisation
The solution, when it came, was unpretentious and practical. Residents introduced fish into the waterlogged mall—tilapia and catfish, with the occasional ornamental carp—using biology to blunt biology. Fish eat mosquito larvae. Fewer larvae mean fewer adults biting through Bangkok’s sticky heat.
Word spread and the fish multiplied. By the mid-2010s, local estimates put the population at roughly 3,000, turning the mall’s atrium into an unlikely urban ecosystem. People dropped by to toss feed from the edges of broken stairwells. On sunny days, broad-backed catfish rolled near the surface like velociraptors in slow motion. Where shop mannequins once posed, schools of glinting tilapia skittered in the light.
Sometimes cities heal their own wounds in strange ways. A ruin becomes a refuge; a hazard becomes a habitat.
The science beneath the spectacle
Using fish to control mosquitoes is older than modern pest control itself. Larvivorous species have been deployed from village jars to rice paddies across Asia, and studies consistently show they can suppress mosquito populations by grazing on larvae before they emerge. In a place like Bangkok—where the rainy season fills canals, courtyards, and construction pits—this approach can fit naturally into daily life.
But a fish-filled mall is not a village jar. The New World pool was vast and largely unregulated, exposed to rain, sun, and runoff. Fish waste and trapped organic matter can deplete oxygen in still water; summer heat can stratify it. Species introduced for one purpose can displace others or stress the system when resources run short. What began as mosquito control edged into a full-fledged micro-ecosystem, a living experiment unfolding under a ripped-open roof.
Public health officials have long warned that ad hoc fixes carry trade-offs. Fewer mosquitoes around one structure is a win, especially amid dengue’s cyclical surges. Yet an unmaintained body of water inside a crumbling building is a safety hazard. The attraction of an “accidental aquarium” drew visitors and curiosity-seekers, raising the risk of falls, contaminated water contact, and additional litter that further altered water quality.
From viral curiosity to city intervention
Photos of the mall’s fish gliding through flooded walkways spread widely about a decade ago, framing the scene as a surreal urban marvel. Tourists and Bangkokians alike stopped to peer through gaps in concrete and metal, some paying nearby vendors for fish food to scatter over the dim water below. This was urban exploration turned communal ritual, equal parts spectacle and neighborhood stewardship.
City authorities eventually stepped in. In 2015, crews drained the standing water and relocated the fish to established ponds. Access points were boarded and locked. Officials cited safety concerns and the need to manage the site responsibly, the same bureaucratic logic that had shadowed the structure since its construction troubles years before.
For the neighbors who had fed the fish and watched them grow, the change felt abrupt but perhaps inevitable. The city’s obligation to prevent accidents and stabilize hazardous properties outweighed the charm of an improvised aquarium. What remained afterward was a dry, echoing shell—no less striking, but stripped of the teeming life that had briefly rewritten its story.
Lessons from a flooded atrium
The New World building’s aquatic interlude illuminates a broader truth about fast-growing cities: systems bend and adapt, whether planners intend them to or not. Bangkok, stitched together by khlongs (canals), overpasses, and back alleys, is a palimpsest where each layer tries to solve the last. In monsoon months the water will come; the city’s response—through pumps, policies, or tilapia—determines what happens next.
There’s also a deeper lesson about public health. Community-led interventions can be nimble and effective in the short term, especially where official resources or attention are stretched thin. Yet lasting solutions demand maintenance and foresight: safe structures, clear drainage, vector control programs that don’t incubate new risks. When improvisation meets infrastructure, the best outcomes come from cooperation rather than collision.
Urban resilience is not just about big projects. It’s the sum of small choices made by neighbors, officials, and the environment itself—each reshaping the other over time.
What a ruin can become
With the fish now gone and the doors sealed, the question turns to what’s next. Around the world, abandoned commercial structures have become parks, markets, and cultural centers—the High Line in New York, a rail-to-trail. Bangkok’s own creative districts show how obsolete spaces can be reimagined into galleries, co-working hubs, and shaded courtyards that cool and connect.
The mall’s location in the old town gives it potential beyond its failed retail past. A restored shell could host wetlands in designed basins instead of accidental ones, using native plants to filter stormwater and provide habitat in a controlled way. Or it could become a civic venue that nods to its strange history, with exhibits on urban ecology and public health, showing how one building’s missteps unfolded into cautionary—and hopeful—tales.
- Design with water in mind, especially in monsoon cities: manage, reuse, and celebrate it safely.
- Match grassroots ingenuity with institutional support so quick fixes can evolve into enduring solutions.