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Earthwatch
High Tech Fish Farming in Your Own Backyard:
A Modern Gardening Eco-System
by Tilapia Mama
Growing tilapia along with edible plants and vegetables in a modern high tech backyard fish farm system is becoming a favorite among urban farmers and home gardeners alike. It’s called aquaponics—combining aquaculture and hydroponics (plants grown without soil) to create a sustainable ecosystem which brings significant benefits and cost savings, especially given current water shortages.
This new technology uses much less water than conventional gardening and you don’t lose much through evaporation either. And, aquaponically farmed vegetables grow much faster than those grown in a conventional garden because organic fish waste is a wonderful balanced fertilizer. Your harvest is organic because you cannot use chemicals—they would harm your fish.
Backyard fish farming works this way: You feed the fish, the fish provide fertilizer for the plants in the water, and the plants and beneficial bacteria then clean the water for the fish. A simple high tech backyard fish farm is easy to manage and creates the ultimate sustainable food source. Plus, if you are vegetarian or vegan, you do not have to eat the fish; just let them live happily.
Tilapia
Of the various kinds of fish used for aquaponics, tilapia are the easiest for beginners to grow successfully. In high demand and sold increasingly in restaurants and markets, tilapia are tolerant to changes in water quality, resistant to disease and can be fed a wide range of feed. The quality of the fish, including the Omega-3/Omega-6 content, is based on what the fish eat. Fish feeds based on corn result in high Omega-6 levels in commercially raised tilapia. Feeding your fish ground flax seed will boost their Omega-3 content.
A simple energy-efficient 200-gallon intensive recirculation backyard fish farm can easily support 50 pounds of fish. These systems are designed to be compassionate to the fish and help them thrive. The fish enjoy fresh clean water at a three-foot depth, community life with other fish, and plenty to eat. Stocking the backyard fish farm every month with new fingerlings results in a food production schedule allowing a daily/weekly harvest of fish. If you don’t want to eat your tilapia, you can just enjoy watching them grow. Aquaponics works fine with pet koi and goldfish, as well.
Fish Water
The key benefit of a backyard fish farm is the fish wastewater, a wonderful fertilizer that is good for hydroponics and watering any plant in the garden. You can use it for drip irrigation for raised beds, your water garden, or fruit trees. Fish water fertilizer contains significant quantities of nitrogen and a healthy balance of all 18 nutrients known to be significant for crop growth. Nitrogen and all the other essential nutrients found in the fish water, plus many more trace minerals, help to increase plant growth and vigor. Fish water also provides more than 60 other trace minerals (not found in chemical fertilizers) which have positive effects on soil biology and crop health. The balanced, moderate levels of nutrients in fish water provide a broad spectrum of fertilizer without the problems associated with excess application of any one nutrient. Fish water does not add salinity to the soil like chemical fertilizers do. It is excellent on every kind of plant and tree. Fish water is best used fresh and frequently because it is mild. Many believe that fish water is the key to a successful crop. Trace minerals improve the food nutrient capability of soil microbes, so the plant roots grow stronger and healthier. It is safe to use anywhere.
Hydroponics
Hydroponics is a natural fit with backyard fish farming. The roots of the plants absorb nitrate-rich water, which act as nutrient-rich plant food. These nitrates, which come from fish waste, would otherwise build up to toxic levels in the fish tanks and kill the fish. But instead, they serve as fertilizer for the plants. The hydroponic plants’ roots function as a biofilter, stripping ammonia, nitrates, nitrites and phosphorus from the water. Clean water is then circulated back into the fish tanks. Because fish waste is used as fertilizer, there’s no need for chemical fertilizers. The money and energy it would take to put those chemicals to work is saved.
The high-nitrogen fertilizer generated through fish waste allows plants to grow lush. Lettuce, herbs, and greens, such as spinach, chives, chard, bok choy, basil and watercress have low to medium nutritional requirements and do well in direct aquaponics systems. Plants that thrive in heavily stock systems are bell peppers, cucumbers, and tomatoes. The ratio of fish water to hydroponic product is 1:4. In other words, for every one part of water and fish, you will have four parts of plant and bed material. Aside from plants and fish, the other major component of aquaponics is the water itself. Carefully monitoring the ammonia level in the water is important to ensure a safe environment for the fish.
How to Get Started
Want to bring fish farming to your backyard food production? Backyard gardeners can set up an inexpensive aquaponics system using recycled materials and easily build a complete DIY system that can grow suitable quantities of fish because of the unique characteristics of tilapia. Cultivating plants and fish through aquaponics is both easy on the environment and on finances. Aquaponics systems don’t use any chemicals, and they require about 10 percent of the water used in regular farming. The systems are closed; that is, once they’ve been filled with water, only a small amount is introduced into the system thereafter due to evaporation.
But how can a water-based system use less water than conventional farming? The answer is the continual reuse and recycling of water through naturally occurring biological processes. Basically, the waste from fish produces natural bacteria that convert waste such as ammonia into nitrate. This nitrate is then absorbed by plants as a source of nutrients. The basic principle of aquaponics is to put waste to use.
Backyard fish farming offers an environmentally beneficial way to cultivate both fish and plants. Anyone can implement basic aquaponics into their backyard gardening. Whether you set up a system on your back patio, your apartment building roof, in your garage, or in your backyard, an aquaponics system can provide a sustainable food source for an entire family.
Tilapia Mama, also known as Sherilin Heise, has been breeding tilapia for five years. She is a Naturalist with the San Diego Natural History Museum and a PhD candidate at Walden University with a BA in Biology from the University of California, San Diego. Tilapia Mama offers My Backyard Fish Farms (MyBFF), which include complete materials, instructions and support, for $149 with discounts available for schools and non-profit organizations. She also conducts workshops in the San Diego area. For more information, contact tilapiamama@cox.net.