In many growing Asian cities, space and water for traditional fish farms are becoming scarce. Patin catfish (a pangasius species popular in Southeast Asia) face these constraints even as demand for protein rises. Rapid urban growth and conversion of farmland to housing mean fish farmers must innovate. One promising solution is aquaponics – a closed-loop system that combines fish culture with soilless crop cultivation. In this method, water from fish tanks is continuously circulated to plant beds, letting plants absorb the fish waste. This approach not only addresses land and water limits but also supports sustainable urban agriculture. For context, FAO notes that by 2030 roughly 60% of the world’s people will live in cities, underscoring the need for efficient local food systems. Aquaponics offers exactly that—a way to grow both fish and vegetables on a small footprint.

Understanding aquaponic technology

Aquaponics integrates aquaculture (fish farming) and hydroponics (soilless plant culture) in a single recirculating system. In practice, fish (here, patin) are raised in a tank or pond where they excrete ammonia and other waste into the water. This nutrient-rich water is pumped into plant growing beds. Beneficial bacteria in the system convert the ammonia first to nitrites and then to nitrates – the form of nitrogen that plants can easily use. In turn, the plants absorb these nutrients for growth. In effect, plants act as a natural biofilter, cleaning the water before it returns to the fish tank.The plants grow rapidly with dissolved nutrients that are excreted directly by fish, taking up the nitrates for fertilizer. In aquaponics, dissolved nitrogen can accumulate to very high levels, so when ammonia from the fish is converted to nitrate, plants get a steady fertilizer supply while the water is detoxified. As a result, toxic wastes stay low: studies show an aquaponic biofilter can reduce ammonia and nitrite in the water to negligible levels, keeping water quality stable and fish healthy. In addition, the plants’ respiration and photosynthesis help aerate the water; when oxygenated water flows back to the fish tank, it further supports faster, healthier fish growth.

Benefits and advantages of aquaponic systems

Aquaponics offers concrete advantages over conventional fish ponds or separate farming of vegetables. First, it saves space. Systems can be stacked vertically or arranged in tight layouts, allowing cultivation on just a few square meters. In fact, household aquaponic units can occupy as little as 2–5 m² (roughly 20–50 ft²) while producing vegetables and fish for a small family. Furthermore, because aquaponics recycles water in a closed loop, it uses far less water than traditional systems. By capturing and reusing almost all fish tank water, aquaponics can cut water needs dramatically. Dissolving waste nutrients through plant uptake reduces discharge to the environment and extends water use, meaning only minimal water replacement is needed for evaporation. In some cases, total water consumption can be as little as 10% of what separate pond-and-garden systems require, making aquaponics ideal for water-scarce urban areas.

Another key benefit is waste recycling and pollution reduction. In conventional aquaculture, fish waste must be removed or it poisons the fish; here it is an asset. The organic waste and unused feed in the fish water serve as a natural fertilizer for the plants. Studies report that aquaponics can recover nearly all the dissolved nutrients from the waste, greatly cutting the need to flush the water (and thus sharply reducing water pollution). Plant roots and the bacteria around them absorb ammonia, nitrite and nitrate, keeping water safe. By using plants as a living filter, aquaponics can reduce toxic nitrogen levels by up to 70% compared to untreated systems, according to reports.

Aquaponics also doubles the yield. Farmers harvest two products: pangasius fish (which reach market size in about 5–6 months) and quick-growing vegetables (often harvested every 25–35 days, depending on the crop). This continuous vegetable harvest provides a fast return while the fish mature. In economic terms, the combined output typically raises overall production value: some analyses indicate growers can boost their income by around 30% compared with raising fish alone.

Spinach grown using an aquaponics system that can be harvested quickly.: Pusat Pelatihan KP

Importantly, aquaponics fits the urban farming trend. Many city residents want to grow their own fresh, pesticide-free food. Since about 60% of people will live in cities by 2030, local food production will be crucial. An aquaponic garden on a rooftop or balcony can supply families with both meat (fish) and produce without long supply chains. In large cities, turning unused space (rooftops, courtyards) into mini-farms helps food security and reduces environmental impact.

Equipment and materials required

Setting up an aquaponic system for pangasius farming does not require high technology or huge land. The basic hardware includes a fish tank (which can be any sealed container or repurposed pond) and a plant grow bed or raft tub (filled with an inert medium such as gravel, clay pebbles or lava rock). A water pump and plumbing are needed to circulate water from the fish tank to the plants and back. An air pump or aerator is also recommended to maintain oxygen levels for the fish. Other necessary components are simple: tubing, valves or siphons to control water flow, and supports or shelves if the setup is tiered.

Equipment needed

For a basic home aquaponic system, the required equipment is relatively simple and often includes everyday items. Key components include:

• Aquarium pump: This circulates water from the fish tank through the grow beds and back. It is the heart of the system, ensuring that nutrients produced by the fish are transported to the plants and that water returns to the pond filtered.
• PVC pipe (Paralon): Plastic piping provides channels for water circulation and also supports the plant containers. Holes are cut in the pipes to hold the pots or net cups where plants grow.
• Recycled plastic bottles: Common plastic bottles can be upcycled into plant pots by cutting off the top. These DIY pots fit into the holes in the PVC pipes and serve as holders for the plants.
• Growing media: Materials like rice husks (sekam) or small pebbles are used inside the pots to support the plant roots and give them structure.
• Seedling media: Sterile, highly absorbent materials such as aquarium filter sponge or rockwool cubes are used to germinate seeds. These keep young plants moist and reduce disease risk.
• Wicking material: Pieces of flannel cloth or cotton rope are placed at the base of each pot to act like a wick, drawing water and nutrients up into the growing media.
• Fish pond or tank: A water-tight container for the fish can be made from a pond liner, a concrete tank, or any available basin. This holds the water and the fish (usually catfish in local systems)

Cultivation materials needed

In addition to equipment, the system must be stocked with fish and vegetable seedlings:

• Pangasius fingerlings: Small juvenile fish (Patin catfish) about 5–7 cm long (roughly 2–3 inches) are used as the aquaculture component.
• Vegetable seedlings: Young plants of leafy vegetables such as water spinach (kangkung), mustard greens (sawi), lettuce, or spinach. These grow in the aquaponics beds and benefit from the nutrients in the fish waste..

Steps to build an Aaquaponic system

The process of setting up a simple aquaponics system can be broken down into four main steps:

1. Prepare the fish pond

Fill the pond or tank with clean water and install an aerator to provide sufficient oxygen. Once conditions are stable, gently release the catfish fingerlings. They should be stocked at an appropriate density (around 20–30 fish per cubic meter) so they have room to grow without overcrowding.

2. Make the plant containers

Construct planters from plastic bottles by cutting off the tops. Fit a piece of flannel or cotton rope at the bottom of each bottle – this will act as a wick to pull water upward to the plant roots. Fill the bottles with your chosen support media (rice husks, gravel, or pebbles). Then insert these bottle planters into pre-drilled holes in the PVC pipes that run above the pond.

3. Germinate and transplant seedlings

Start vegetable seeds in a moist, sterile medium like rockwool or filter sponge. These media retain water well and protect young plants from disease. Choose seeds with a high germination rate (at least 80%). Once the seedlings have grown two true leaves and are well-established, transfer them into the prepared bottle pots on the PVC channels.

4. Set up the water flow

Install the aquarium pump to draw water from the fish pond into the PVC piping where the plants sit. The water flows through the plant roots and media, then drains back into the pond, effectively filtering the water. This creates a continuous circulation that maintains good water quality for the fish and delivers nutrients to the plants.

Harvest time

One advantage of an aquaponic system is the staggered harvest schedule for plants and fish. Leafy vegetables like water spinach, lettuce, or mustard greens usually mature quickly – often in about 25–35 days after planting, depending on variety and conditions. Many home-scale systems use planting densities around 20–30 plants per square meter, yielding roughly 2–3 kg (4–6 pounds) of fresh vegetables each cycle. This rapid turnover ensures a steady, ongoing supply of greens for home consumption or sale at local markets.

By contrast, the catfish require a longer growth period. Pangasius catfish typically reach an edible size (around 600–800 grams per fish, about 1.3–1.8 pounds) in roughly 5–6 months. At a stocking density of 20–30 fish per cubic meter, this produces about 15–20 kg (33–44 pounds) of fish per harvest cycle. The difference in timing between the vegetable and fish harvests is a key advantage: growers can enjoy monthly vegetable harvests for immediate income or family needs while waiting a few more months for the larger, higher-value fish harvest.

Challenges and hopes

Despite its many benefits, aquaponics still presents real challenges for newcomers. The initial investment in equipment (pumps, pipes, filters, grow media) can be relatively high for small-scale farmers. Moreover, running the system requires technical knowledge – growers must monitor water quality, balance the nutritional needs of fish and plants, and perform regular maintenance to keep the system stable.

Introducing aquaponics and ornamental fish farming to students at Al Hidayah Elementary School, Dawuan Village, Majalengka Regency, West Java: Luhkan Majalengka/Nina Rosita

Still, many farmers and urban gardeners view aquaponics with optimism. It offers a productive way to grow food even on limited land and with limited water – issues that affect many large cities. Aquaponics also encourages a cleaner environment by recycling water and organic waste. In this way, it supports a more sustainable future: households can stay productive, generate income (or food), and minimize pollution. Many advocates hope that, over time, wider adoption of aquaponics will enhance food security and create more resilient urban farming systems.