aquaponic organic

Aquaponics can be loosely described as the combination of aquaculture and hydroponics. A natural environment where fish are kept healthy and happy and provide for a chemical free environment, without the use of costly fertilizers and pesticides. Fruiting plants and vegetables take advantage of the nutrients provided by the fish and in return clean the water in a symbiotic relationship.

This system provides healthy fresh food on the weekly menu as well as creating a relaxing hobby from the two most popular pastimes in Australia, gardening and fishing.

Hydroponic systems rely on the careful application of man-made nutrients for the optimum growth of plants. The nutrients are made from mixing together a concoction of chemicals and trace elements to form the 'perfect' balance. Water in hydroponic systems needs to be discharged on occasion as the salts and chemicals build up in the water which can become toxic to the plants.

Aquaculture systems focus on maximizing growth of fish in tank or pond culture. The fish are usually heavily stocked in the tanks, often 10kg in 100L of water. The high stocking rates often mean that the tank water becomes polluted with fish effluent which gives off high concentrations of ammonia. Water has to be discharged at a rate of 10-20% of the total volume in the tank on a regular basis. This water is often dumped and may pollute sensitive ecosystems and destroy waterways.

Aquaponics combines both systems and in doing so cancels out the negative aspects of each. Instead of adding harmful chemical solutions to grow plants, aquaponics uses highly nutritious fish waste that contains many nutrients required for optimum growth. Instead of discharging water, aquaponics uses the plants and the media in which they grow to clean and purify the water, after which it is returned to the fish tank. This water can be recirculated and only has to be topped up when it is lost through transpiration and evaporation.

Fish are a key element in all aquaponics systems as they are required to produce feed for the plants. All fish produce waste, the more food that they consume the more effluent they will discharge into the water. Any fresh water fish can be used, such as Barramundi, Rainbow Trout and Silver Perch or even goldfish, however it is important to keep in mind their specific needs and characteristics. Some fish need cool temperatures to thrive and are therefore best suited to winter months or colder areas. Other species prefer warmer temperatures and are best suited to summer months and warmer areas.

Plants are the purifiers in an aquaponic system and therefore are a major element. The plants role is to clean the water for the fish. Plants that are best suited to this are vegetables, fruits and herbs as they consume large amounts of nutrients. Other plants can be used but consideration should be given to whether or not they lay dormant during the year (a period of low growth and low nutrient uptake). Be mindful of plants that have invasive roots such as mint and watercress as they are very hard to remove once they are established. Plants need beneficial bacteria to access the fish effluent.

Beneficial bacteria are what combine aquaculture and hydroponics, without bacteria the system would not function. The bacteria occur naturally in air, water and soil and will begin colonising the system on all surfaces, as soon as ammonia (fish effluent) is present. The process is called the nitrogen cycle and leaves the water clean after the plants have extracted the nitrates.

By working with nature we encourage natural processes that can be monitored and recorded for lessons in schools on integrated science, biology, horticulture, health, society and environmental issues. Aquaponics is ideal for the backyard vegetable patches, schools, universities, restaurants, hotels and almost anything.

Aquaponics systems are gaining popularity and can be used to grow food for personal use or for commercial production. The most popular fish grown in aquaponics systems is tilapia. However, some growers have had success growing largemouth bass, perch, carp, crappies, bream, and some ornamental fish such as Koi and goldfish. The plants that are traditionally grown in these systems are lettuce, other salad greens, and succulent herbs such as basil. Some commercial systems that feature densely stocked fish tanks can grow tomatoes, cucumbers, peppers, and even melons. Both systems are in a controlled environment, meaning light and temperature are controlled. The primary crop is the vegetable and the fish are secondary, meaning commercially.