Aquaponic Fish Facts


| 5/14/2013 4:33:00 PM


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Aquaponic gardening is a fascinating way to grow two food products – vegetables and fish – together in an organic, symbiotic ecosystem. Beneficial microbes convert the fish waste into nutrients for the plants growing in a soil-less medium, and the plants return clean water to the fish.

Growing vegetables is a familiar process for most of us, especially if we were lucky enough growing up to help with the family garden every summer. But growing game fish for food is unfamiliar to most gardeners and can be somewhat intimidating. Even for experienced aquarium hobbyists, growing a plate-sized tilapia is a whole different animal.

Aquaponic Fish 

The key to growing fish for food, or any fish for that matter, in aquaponics is to consider what stresses the fish in a captive environment, and lessening, or eliminating, it. There are three categories of fish stress: physical, chemical, and biological.

Physical Stress – This includes all the environmental conditions that we control for our fish, the most important of which is temperature. All fish have a temperature range within which they will thrive, and a wider range within which they will survive. Fish are cold-blooded animals and do not have the ability to expend energy to maintain a constant internal body temperature like we do. They are completely at the mercy of the temperature of their surrounding water. If that water temperature goes outside of their optimal, or “thriving”, range they will eat less, or stop eating all together, and they become more susceptible to disease. That said, this is sometimes carefully employed as a technique called “cold banking” in order to slow down their growth rate. Cold banking is especially effective with fingerlings, when you are trying to stagger your fish production.

Another form of physical stress is sudden exposure to light and vibration. Fish are alarmed when we flip on a light switch and shock their world instantly from night to day. They will often start banging against the walls of the tank to escape the light. However, just like with cold banking, this sensitivity to light can be used to the aquaculturalist’s advantage by employing a technique called “phase shifting” whereby you trick the fish into thinking that it is spawning season (or not) by timing the amount of light they get during the day to mimic the season in which they normally spawn (or not).




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