Aquaponics: Learning by diving into the tank

Sustainable Aquaponics: A Small-Scale Experiment in Phnom Penh, Cambodia

In the heart of Phnom Penh, Cambodia, a small-scale aquaponics experiment is underway, aiming to demonstrate sustainable food production using a 1000-liter tank and tilapia fish. This approach combines aquaculture and hydroponics, creating a symbiotic environment that benefits both plants and fish. This blog post shares insights from the experiment, its setup, challenges, and potential benefits for urban farming in Cambodia.

Setting Up the Experiment

The core of the experiment is a 1000-liter tank stocked with red tilapia, a hardy and fast-growing fish species popular in Cambodian cuisine. The tank is connected to a hydroponic system where leafy greens and herbs will be cultivated without soil. Fish waste provides essential nutrients for the plants, while the plants help filter and purify the water, creating a closed-loop ecosystem.

Key Components:

• 1000-liter IBC tote converted to a fish tank in a chop and flip design
• Tilapia fingerlings
• Biofilter made from LECA to convert ammonia from fish waste into nitrates
• Grow beds with LECA media for plant roots
• Water pumps to circulate water between filters, fish tank and grow beds
• Houseplants initially, then leafy greens like lettuce, and bok choy as crops

Process and Observations

After introducing tilapia into the tank, the system was gradually balanced to ensure water quality and nutrient levels supported both fish health and plant growth. Regular monitoring of pH, ammonia, nitrite, and nitrate levels was essential to maintain a stable environment.

Within a few weeks, the plants thrived, showing vibrant growth without the need for chemical fertilizers. The tilapia adapted well to the controlled environment, growing steadily and providing a potential source of protein.

Challenges Encountered

• Initial water quality fluctuations required careful adjustments to biofiltration and feeding schedules.
• Maintaining consistent water temperature was difficult due to Phnom Penh’s tropical climate, necessitating shading and cooling.
• Quickly added an air pump to keep oxygen level high because of high temps.
• Limited access to aquaponic-specific materials and knowledge in the region slowed initial setup and troubleshooting.
• Lack of natural light for plants in the tank location and necesary shading.
• Unexpectedly high survival rate for tilapia has lead to overcrowding and ineffective filtration of solid waste.

Benefits and Future Potential

This small-scale aquaponics experiment highlights several benefits for urban farming in Phnom Penh:

• Efficient use of space, ideal for densely populated urban settings.
• Reduced water usage compared to traditional agriculture.
• Dual production of fish and vegetables, enhancing food security.
• Potential for local communities to adopt or adapt for sustainable farming practices with minimal environmental impact.

The 1000-liter tank and tilapia-based aquaponics system in Phnom Penh serve as a promising model for sustainable urban food production in Cambodia. While challenges remain, the experiment underscores the viability of aquaponics as a means to address food security, resource efficiency, and environmental sustainability in growing cities. With further development and community support, such systems could become a staple of urban agriculture in Cambodia’s future.