AMWUA Blog

Dec 24 2018Share

No Fish Tale: Avondale Tilapia Farm Saves The City Money

By Warren Tenney

The City of Avondale’s Water Department raised 2,800 fish this summer with help from Blue and Stripe, the most prolific couple in the city’s tilapia breeding colony. The tilapia help clear algae from the 21 connected lakes that are part of a 72-acre wetlands project within Avondale’s Crystal Garden residential development. By breeding its own tilapia, the city has cut the cost of stocking the fish by 80 percent. 

Avondale’s Crystal Garden Lakes are filled with water delivered by Salt River Project. The wetlands act as a surface water treatment plant by naturally treating the water before storing the water underground in the city’s aquifer. Using algae-eating fish is an organic way to keep lakes clean without resorting to chemicals. Avondale keeps Chinese Carp and Channel Cat fish in the lakes to clear the algae from the bottom. Tilapia are essential because they prefer to eat the algae on the sides and surface of the lakes. They do so aggressively, keeping the lakes looking and smelling good. At its prime, a tilapia eats twice its body weight in algae, one to two pounds every day. Tilapia also eat bugs near the water’s surface. 

The tilapia die once the temperature dips to 55 degrees and must to be restocked every spring. It had cost the city about $25,000 annually to keep the lakes stocked with the fish. Every spring, Avondale bought 4,000 to 5,000 tilapia from a contractor in the Southeast. Many suffered injuries and some died during the trip across the country. Others arrived too small and were eaten by other predatory fish in the lakes. Tilapia can and do breed in the lakes, but their offspring are quickly gobbled up by other fish. So, the tilapia population decreased throughout the warmer months. Sometimes algae can grow suddenly in one lake or another and the city would need an additional 300 to 500 of the tilapia in a hurry. The city often couldn’t find the fish it needed in time for a quick clean up – or at all. 

Raising tilapia saves the city money and gives it the flexibility it needs to keep the lakes clear of algae. Avondale invested about $9,000 to set up a small tilapia farm in a 20-foot by 40-foot space inside one of its buildings in a water operations yard. It will cost about $4,000 a year to maintain the system, including the hour or so of employee time every morning to tend to the operation. The farm can provide all the large, healthy tilapia the city needs each spring and give it the flexibility to add hundreds of fish as needed throughout the summer months. 

Avondale’s Aquaculture Project or fish farm starts with a good breeding colony of one male, Blue, and four females in a large aquarium. This aquarium’s temperatures must be carefully regulated. A female tilapia can produce a batch of 800 to 1,000 babies every two weeks. When temperatures are raised in the colony’s aquarium, the fish are more likely to breed. With the right conditions, a female fish will release her eggs to be fertilized by the male fish. The female fish quickly gathers the fertilized eggs into her mouth where they are protected and grow into tiny swimming tilapia in about seven to nine days. For those seven to nine days, Stripe protects her eggs at great cost to herself, warding off other females and not opening her mouth to eat all week. (On the other hand, Emily hasn’t yet successfully held onto her offspring. Emily will be taken from the breeding colony this spring and placed in a lake.) The female’s tiny offspring are coaxed from her mouth into a net and placed in a small aquarium where they are fed fish food ground in a coffee grinder. Avondale’s operation saves more than 95 percent of these tiny fish. The fish are fed by automated feeders and grow and graduate into a larger aquarium until they are big enough to be placed in the Recirculating Aquaculture System. 

The Recirculating Aquaculture System consists of three 300-gallon plastic tubs. Water continually flows out of the tubs and into a two-step automated cleaning system. One self-cleaning system filters out the fish waste matter and another clears the water of ammonia before it is recycled into the tanks. This closed system saves gallons of water and keeps the fish healthy. This is where Stripe’s first winter brood of 1,106 juvenile tilapia is waiting for spring. When that time nears, Avondale employees will grow these fish to about one-half pound each by providing them more space, more oxygen, more food and warmer water. The city needs about 4,000 healthy tilapia fish throughout the warmer parts of the year. 

Avondale’s tilapia are the same type that you would find on a restaurant menu. Avondale allows people to fish the lakes, but they are not permitted to keep what they catch. The Arizona Department of Game and Fish took 60 of Avondale’s tilapia to examine them and make sure they were disease free and otherwise healthy. Birds of prey can catch and transfer fish from one lake to another, so the state is careful to monitor the health of any stocked fish. Yes, Avondale is raising healthy tilapia, saving money, keeping their lakes clean and the neighbors happy. 

For 49 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit www.amwua.org.

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