Aquaponic Gardening

Food Justice: End the Corporate Exploitation of ‘Food Deserts’
April 15, 2013

Aquaponic gardening is a terrific way to grow your own organic veggies and chemical free fish.  Let’s take a moment to  ponder the subject of what to feed your “wet” pets so that you can economically harvest the best. The subject of duckweed usually will come up in any conversation when folks passionate about aquaponics get together … it seems that his tiny aquatic plant can make a big impact!

Duckweed is a species of small floating aquatic plants found worldwide.  It is often seen growing in thick, blanket like mats on still or slow moving, nutrient rich fresh or brackish waters.  Anyone who has ever had duckweed “sneak” into an aquarium or pond knows that this tiny plant can double their mass in under 2 days given the right conditions … this is faster  than almost any other higher plant.  It is for this reason duckweed is considered an invasive plant in many parts of the country and is on the “hit” list in some states.
Now the real dilemma regarding duckweed is whether it is something you should be feeding it to your fish in your aquaponics system.  The nutritional value of duckweed varies, but most species have protein contents in the range of 15-45% which is good and duckweed is a convenient feed for fish.
  • It can be readily grown locally
  • It can be fed fresh and since it floats, it will be consumed by your fish and not decay at the bottom of your system.
  • It is used very efficiently by fish such as tilapia and carp, but other species might well cope with duckweed as a component of the diet since it is particularly low in fiber and high in protein when grown under ideal conditions.
  • It is relatively inexpensive to produce or may be regarded to have no cost where the opportunity costs of family labor are not taken into consideration.

Fish such as Tilapia and Yellow Perch are raised in a large tank of water.  Growing Power uses Tilapia and Yellow Perch in our aquaponics systems because they are relatively easy to raise and because we can market them to restaurants, market basket customers, and they are a favorite in ethnic markets. Originally found in Africa, Tilapia has been farmed for more than 2,500 years.  Tilapia is a perfect fish for aquaponics because of its rapid growth, large size, and because it tastes great. This hardy fish can adapt to most any condition with the exception of water temperature.  Tilapia prefer warm water – at least 75 degrees Fahrenheit.  It takes about 9 months for our Tilapia to grow to a harvestable size, about 1.5 pounds.

What does Tilapia eat?  At Growing Power, we feed our fish duckweed, ground-up salad greens from the greenhouse, worms, and Tilapia love to eat algae from the side of the tank.