What is Aquaponics? Growing Fish and Vegetables Together

What aquaponics is and how the cycle works

Aquaponics is a food production method that combines aquaculture — fish farming — with hydroponics, the growing of plants in water without soil. The two systems are linked in a single recirculating loop that makes each one more efficient. Fish produce ammonia-rich waste. Beneficial bacteria in the system convert this ammonia first to nitrite and then to nitrate — the same conversion that occurs in a healthy natural water body. Plants growing in or above the water absorb these nitrates as fertiliser, cleaning the water in the process. The clean water then cycles back to the fish.

The result is a near-closed-loop system that produces two food outputs simultaneously: fish protein and plant produce, often vegetables and herbs. Because the water is continuously cycled and cleaned rather than discharged, aquaponics typically uses 80 to 90 percent less water than conventional soil agriculture producing equivalent yields. No synthetic fertilisers are needed — the fish supply the nutrients the plants require. In most aquaponic systems, pesticides are also avoided because they would harm the fish.

Water efficiency — why it matters in Israel

Israel's agricultural sector accounts for a large share of total national water consumption, and the country's national water strategy involves a major ongoing shift toward recycled wastewater for irrigation — approximately 50 percent of agricultural water in Israel now comes from recycled sources, primarily from treatment plants such as SHAFDAN. Aquaponics represents a complementary approach: rather than treating water after use, it designs food production systems that require far less water to begin with.

For urban and peri-urban food producers, aquaponics offers a route to meaningful food production in locations where land and water are both scarce and expensive. A well-managed aquaponic system on 50 square metres can produce a substantial continuous harvest of leafy greens and herbs alongside a regular fish harvest, using water volumes that would not sustain equivalent yields in open-field agriculture.

Common system designs

The three most common aquaponic configurations are flood-and-drain (also called media-bed), deep water culture (DWC), and nutrient film technique (NFT). In a flood-and-drain media-bed system, grow beds filled with gravel or clay pebbles are alternately flooded and drained with fish tank water on a timed cycle. Plants grow in the media, and the media also hosts a substantial proportion of the beneficial bacteria responsible for the nitrogen cycle. This is the most forgiving configuration for beginners.

Deep water culture floats plant rafts on the surface of a long shallow channel of fish water. This system is highly productive for leafy greens and herbs — lettuces, basil, spinach, watercress — and is the configuration most often used in commercial aquaponic operations. Nutrient film technique circulates a thin film of water along channels in which plant roots hang; it is efficient but requires more careful management of flow rates and is less tolerant of pump failures.

Which fish and which plants work best

The most widely used fish in aquaponic systems globally are tilapia, trout and carp. Tilapia is particularly well suited to Israeli conditions: it tolerates warm water temperatures (20 to 30 degrees Celsius), is omnivorous, grows quickly and produces good quality protein. It is also a familiar edible species in Israel. Carp, which tolerates a wide range of water conditions, is a practical choice for beginners. Trout requires cooler water and is more appropriate for higher-altitude or winter systems in Israel.

Plants that perform well in aquaponic systems are generally fast-growing species with high nutrient demand. Lettuces, spinach, kale, basil, mint, chives, coriander and other herbs are consistently reliable producers. Fruiting crops — tomatoes, peppers, cucumbers, aubergines — can be grown aquaponically but require more nutrient-dense systems, typically with higher fish stocking densities or supplemental iron, which is often the limiting micronutrient in aquaponic systems.

Home and urban applications

Aquaponics scales from small indoor units that fit on a kitchen counter to large commercial greenhouse operations. A balcony system of one to two square metres can produce enough herbs and salad greens to meaningfully supplement household consumption year-round, along with a small number of fish. The key design requirement for indoor and balcony systems is structural: fish tanks and growing media are heavy when full, and the structure supporting them must be rated accordingly.

Pre-built aquaponic starter kits are available from various suppliers in Israel and internationally. Open-source designs are also widely available for those comfortable with DIY construction. A small system requires a pump, an air pump, lighting (indoors), a fish tank, grow beds and fish feed. Electricity consumption — primarily for the pump and lights — is the main ongoing operating cost beyond fish feed, and should be factored into the economics of any home system.

What to watch out for

The most common challenge in new aquaponic systems is the nitrogen cycle establishment phase. A new system has no established bacterial colony, so ammonia from fish waste builds up before bacteria develop in sufficient numbers to convert it. This process — called cycling — typically takes three to six weeks. Running the system without fish during this phase, or starting with a very low fish stocking density, avoids fish losses from ammonia toxicity.

Aquaponics requires consistent monitoring of water chemistry: ammonia, nitrite, nitrate and pH levels should be checked regularly, particularly in the first six months. pH management is especially important, as the system operates optimally in a relatively narrow range (6.8 to 7.2) that must balance the preferences of fish, plants and bacteria — all of which have slightly different ideal conditions. Once established and stable, a well-designed system requires relatively little daily intervention, but the establishment phase demands attention.