Once an aquaponics system is built and can run without complications, such as leaks or overflowing of a tank, two key components that must be added to the system: plants and fish. Fish are an integral part to an aquaponics system. Fish constitute the “aqua” in aquaponics, referencing aquaculture, or fish-farming, but they also represent something much greater than that: being the source of nutrients and food for the plants.
The primary function of growing fish in an aquaponics system is to provide the necessary nutrients for plant growth in the growing bed of a system. Subsisting in a separate tank from where the plants grow, the fish live and produce waste. This waste is then filtered and travels through the plant bed where plant roots uptake these nutrients for purposes of growth. As this water travels through multiple filtration systems and the plant bed, the majority of toxins and excess nutrients are drawn out. By the time the water cycles back into the fish tank, it enters as clean, livable water for the fish.
Choosing a fish species to use is an important step in building a successful and productive aquaponics system. Two important factors to consider when making this decision include the climate of where the system will be located as well as the overall goal regarding the fish. Some species present themselves as better options depending on if the fish will be grown as a food source. Nonetheless, three great options for fish include carp, tilapia and trout.
Carp are the most widely cultured fish in the world and are primarily cultured in Asia. Recently, carp have caused environmental problems because of their invasive nature and fast reproductive abilities. However, these are both positives when considering carp as an option for use in a system. Carp are a resilient breed that have a remarkably fast reproductive ability and are able to adapt to many different environments. Despite this, these fish aren’t the best edible option.
Tilapia are a very widely used fish species in aquaponics systems and are the second most cultured fish in the world. These fish are popular in aquaponics systems because they’re both easy to breed and grow quickly. Additionally, tilapia are a fairly resilient fish species and can withstand relatively poor water conditions. The one downfall to using this fish is the temperature constraint. Tilapia are warm water fish and are much better suited to survive in warmer climates and water temperatures.
Trout are a great fish species to use in a system where the climate is cooler, and the water temperature is cold. These fish can sustain themselves in a system that runs between approximately 10-20 degrees centigrade. In addition to this, trout grow at an astoundingly fast rate and provide growers with a great food conversion ratio.
Overall, there are many great fish options available, but it is important to research these available options to ensure that the growth and ability of the fish, plants and system is maximized.