Dr Sarath Obeysekera Blue Economy advocate 

1 Sri Lanka’s ancient reservoirs are a national asset

• Sri Lanka has more than 10,000 irrigation tanks and reservoirs, most of them built or restored by ancient kings over the last 2,000–2,500 years.  
• Historical studies identify about 44 major ancient reservoirs built by the ancient kingdoms, many of which remain in use today after rehabilitation.  
• The country has one of the highest densities of man-made reservoirs in the world.  

2. Which reservoirs generate hydropower?

Only a relatively small number of the larger modern reservoirs are used primarily for hydropower, including:

• Victoria Reservoir
• Kotmale Reservoir
• Randenigala Reservoir
• Rantembe Reservoir
• Samanalawewa Reservoir
• Castlereagh Reservoir
• Maussakelle Reservoir

Most of the ancient reservoirs—including Parakrama Samudraya, Kala Wewa, Minneriya Tank, Kaudulla Tank and Nachchaduwa Tank—continue to serve mainly irrigation while also supporting fisheries.

3. Inland fisheries are no longer a small sector

According to the Ministry of Fisheries:

• Marine fish production (2024): about 308,430 metric tonnes
• Inland fisheries and aquaculture: about 102,330 metric tonnes
• Inland fisheries therefore contribute about one quarter of Sri Lanka’s total fish production.  

There are also:

• nearly 95,000 inland fishers
• almost 84,000 inland fishing households  

This demonstrates that inland fisheries are already economically significant.

4. Reservoir fisheries have enormous potential

Studies by the FAO show:

• Reservoir fish production can exceed 250–300 kg per hectare annually, with some reservoirs producing much more under proper management.  
• Most reservoir fisheries rely on natural breeding populations, making them relatively inexpensive compared with intensive aquaculture.  

5. Why consumers hesitate

You also raise an important marketing issue.

Many Sri Lankans hesitate to buy freshwater fish because they worry the fish may come from polluted waters such as:

• Beira Lake
• Weras Ganga
• polluted stretches of the Kelani River

In reality, much of the freshwater fish sold in Sri Lanka comes from clean irrigation reservoirs in the North Central, Eastern, North Western and Uva Provinces. However, there is little product traceability or branding to reassure consumers.

6. What the Government could do

The Ministry could significantly expand the inland fisheries sector by:

• Developing certified Reservoir Fresh Fish” branding.
• Introducing traceability showing the reservoir of origin.
• Establishing hygienic collection centres and cold-chain transport.
• Promoting reservoir cage culture where environmentally appropriate.
• Integrating fisheries into irrigation management instead of viewing reservoirs solely as irrigation assets.
• Training farmer organizations to manage fisheries sustainably.

Nutritional advantage

Freshwater fish such as tilapia, carp and freshwater catfish are:

• rich in high-quality protein,
• good sources of calcium (especially when small fish are eaten whole),
• rich in phosphorus and essential minerals,
• contain beneficial omega-3 fatty acids,
• generally more affordable than many marine fish.

Conclusion

Sri Lanka’s ancient kings built reservoirs primarily to irrigate fields, but these same water bodies now represent an underutilized blue economy.” While hydropower and irrigation remain essential, reservoir fisheries can simultaneously improve rural incomes, enhance national nutrition, reduce food costs and strengthen food security. Greater investment in inland fisheries would honour the vision of the ancient hydraulic civilization by ensuring that every reservoir serves multiple productive purposes, rather than irrigation