In the brackish ponds of Lala, Lanao del Norte, researchers from the Brackishwater Fisheries Research and Development Center (BFRDC) of DA-NFRDI are reimagining aquaculture. Their experiment is deceptively simple: raise giant freshwater prawns and red tilapia together. The results, however, have the potential to change how coastal communities farm fish, and address some of the industry’s most significant challenges today.

New kind of pond

Polyculture of prawns and tilapia is not new. Farmers and researchers have long recognized the benefits of raising these species side by side. What makes this experiment groundbreaking is that it is the first grow-out culture carried out in a brackishwater environment.

Traditionally, polyculture trials have been done in freshwater ponds. By moving into brackishwater, where salinity fluctuates between 14 and 17 parts per thousand, researchers tested the strength of both species under more challenging conditions. This innovation opens the door to more efficient use of vast, underutilized brackishwater ponds across the Philippines.

A study on early-life culture and gonadal development of giant freshwater prawn in 2022 reported that, the species locally known as ulang, udang, or paje, is indigenous to the Indo-Pacific region, and is found mostly in Malaysia, Thailand, India, Bangladesh, and Myanmar.

According to another study, the worldwide expansion of giant river prawn farming is relatively well documented. Modern aquaculture of the species began in the 1960s. Since the discovery that ulang larvae require brackish water to survive, scientists have developed techniques that enable the commercial production of post larvae (PL).

Balancing act

Over 120 days, BFRDC researchers tested different stocking densities. Some ponds had prawns alone, while others had prawns plus tilapia, ranging from 300 fish to more than 1,000.

The findings were clear. First, prawns grew bigger when tilapia were present. Sharing the pond seemed to help prawns thrive. Second, tilapia did best at moderate numbers. With the right amount of fish, they grew large and healthy. But overcrowding slowed their growth. Third, survival rates dropped at high densities. Too many animals meant stress, competition, and even aggression.

The sweet spot? A moderate mix of prawns and tilapia.

Profits in the pond

The study’s cost analysis showed that ponds with the optimal levels of ulang and tilapia yielded the highest profit, estimated at over PhP 7,000 in 200 square meter pond. Overcrowded ponds produced more fish overall, but feed costs ate into earnings. Prawns raised alone actually lost money.

This means polyculture isn’t just biologically sound, it’s economically smart. And with giant freshwater prawns commanding high local and export demand but suffering from limited supply, and red tilapia enjoying strong demand in local markets, the timing couldn’t be better.

Why it matters

The implications of polyculture in aquaculture extend well beyond the success of a single experiment. According to the Philippines Statistics Authority, high market demand with limited supply makes prawns a premium commodity, but production remains low, while tilapia caters to everyday consumption. By cultivating both species together, farmers can tap into multiple markets simultaneously, diversifying their income and reducing financial risk.

Underutilized ponds also stand to benefit, as many brackishwater ponds currently operate under inefficient monoculture systems. Polyculture maximizes pond usage, allowing farmers to make the most of available space, water, and feed resources. In addition, climate resilience is a major advantage of polyculture systems. Both tilapia and prawns can tolerate varying salinity levels and withstand changes in water conditions, making the system more adaptable to environmental stress and extreme weather events.

Finally, efficiency gains are significant: monoculture farms often face disease outbreaks, feed wastage, and lower yields, whereas polyculture reduces these risks, optimizes resource use, and ultimately increases overall productivity. Together, these benefits present a compelling case for shifting toward more integrated, sustainable aquaculture practices.

Looking ahead

BFRDC researchers emphasized that further studies are needed to refine stocking strategies and explore effective salinity management. Yet the takeaway is clear: prawns and tilapia can thrive together, and when managed wisely, they offer Filipino fish farmers the chance to increase earnings while maintaining sustainable ponds. “It’s about balance. With the right mix, farmers can grow more, waste less, and earn better,” explained NFRDI Senior Science Research Specialist and Project Leader Marnelli Rubia.

Polyculture of prawns and tilapia may not be entirely new, but achieving it successfully in brackishwater ponds is a breakthrough. This pioneering grow- out experiment, launched in April 2025, builds on decades of global aquaculture knowledge, demonstrating that the right balance can unlock the potential of underutilized ponds, meet high market demand, and establish a climate-resilient aquaculture system for the future. ### (Norvida Cruz-Gatdula)