Aquaponic production of high-value species in a greenhouse

Wastes from aquaculture can pollute the environment if not used in an integrated system. One integrated system is called aquaponics which is a combination of aquaculture (raising fish) and hydroponics (growing plants without soil). It is considered an environment-friendly culture system because the wastewater from raising fish is utilized for plant growth, as the wastewater is really not a waste but nutrients for plants. However, aquaponics may not be profitable if the species grown have low market price. Most aquaponic systems use tilapia which has a low market price (less than 2 rials/kg). High-value species need to be tested in an aquaponic system. One fish species that has high market price is koi carp which is imported and being sold at 5-7 rials per piece (juvenile size) in pet shops in Oman. Recognizing this, I and my students in the Fish Breeding course attempted to induce the spawning of the broodstock of this fish species which the Department of Marine Science and Fisheries bought from Thailand four years ago. We were successful in breeding the fish and have produced hundreds of juveniles. This good news has been published in Oman Tribune and Muscat Daily on April 1, 2017. Our initial experiments in non-greenhouse condition show that koi carp can grow well with mint in an aquaponic system. Our previous aquaponic experiments in non-greenhouse condition since 2014 using tilapia in combination with lettuce, tomatoes, chili pepper, eggplant, cabbage, mint and the ornamental flowering plant Petunia have shown that most of these plants grow well only in winter (Dec-Jan) in Oman while mint can grow well year-round, even in summer (Gallardo, 2017). However, mint has low market price in Oman. Many high-value plant species that can grow well in an aquaponics system require a suitable temperature below 30anddeg;C but in Oman, the temperature is above 30anddeg;C most of the year, thus there is a need to use a temperature-controlled greenhouse. With the approval of CAMS Dean, we can use a greenhouse at the Agricultural Experiment Station (AES), to test high-value species of plants that require cool and stable temperature. These are strawberry, lettuce, cabbage, and other plant species including expensive ornamental plants such as orchids. However, there are no funds yet to test these plants in combination with koi carp and other expensive freshwater fish species in an aquaponic system inside a greenhouse.