One day, Édson Henrique do Amaral told his friends he wanted to invest in fish production on his farm, in Paraná, a state in Southern Brazil. They all laughed. The city he lives in is known for its cold weather, and they thought this aspect was incompatible with traditional fish farming.
After studying hard, Édson developed a system that includes suspended tanks that look like large circular pools, with a capacity to produce 10 tons of live fish per month. To solve the low-temperature problem, he uses a greenhouse that keeps the tanks warm. The whole structure is sustainable, supported by solar energy and water recirculation.
“Some call me crazy, reckless. Others call me visionary, bold. I see fish farming in Curitiba as a great opportunity,” says Amaral, who runs the business with his wife, Milene Melo Amaral. “Our idea is to have fish all year round, including in the colder months, from June to September, with this greenhouse system. Thus, we will have a continuous supply,” he adds.
Most of the structure is used in the production of tilapia (or St. Peter), the flagship of Paraná fish farming. Édson is planning on adding more species to the system, like pirarucu—a typical Amazonian fish—, dourado, tambacu, and pacu. In another field, the farmer is preparing to begin producing giant shrimps. The 6 thousand larvae will live together with the tilapias, in a consortium. “The shrimps live on the bottom of the tank. The tilapia, on the other hand, stay in the middle part of the pond. So, this hybrid culture is possible and it optimizes our structure,” he says.
Sustainability in fish farming
The complex’s productivity is noteworthy. While in an excavated tank it is possible to raise 1 kilo of fish per cubic meter of water, in Amaral’s model the density is 20 times greater. “To produce in excavated tanks the quantity of fish we have, we would need 15 thousand square meters of water. With hanging tanks, anyone who has a backyard on their farm can adopt them and have a reasonable income,” the fish farmer explains.
The water—about 1.3 million liters—comes from artesian wells and pits. The complex is equipped with a recirculation system, in which the water that passes through the fish tanks is directed to a kind of treatment center. This “center” is installed next to the greenhouse and is formed by tanks dug in levels, with a natural filtering system. There, the animal waste is sedimented and, driven by ten motors, the water returns to the fish tanks. In addition, oxygen diffusers maintain favorable conditions for the aquatic fauna.
“This water will be recirculating in the system for at least four years. Only after that will we need to replace it,” explains Amaral. “Our system is completely ecological and sustainable. We do not use water from rivers, and this water is not discharged into nature. And all of this is powered by solar energy,” he points out.
Training for fish farmers
Brazilian fish farmers are assisted by SENAR, a training and support institution that offers, free of charge and with a final certificate, courses like “Fish Farming: Culture System”—this one in Parana’s unit. The local producers receive information about legislation, installation, water quality monitoring processes, fish biometry, harvesting, slaughter, commercialization, and many more.