Know Your Fish Weight

Fish Weight

In an aquaponic system your plants are ultimately eating fish food, the fish are just the middle man. Therefore, its helpful to know how much your fish weigh to calculate how much they are eating and how much plant growth they can support.

The key ratio of an aquaponics system is fish food to plant grow space. Leafy green plants will require between about 20 and 50 grams of fish food per day per square meter of grow space (assuming a fully utilized space). Fruiting plants like tomatoes and cucumbers will require a higher ratio between 50–80 grams per meter squared per day. (Somerville, et al 2014)

Once you figure out how much fish food your plants require, you work backwards to figure out how much fish you need. And this is based on a standard fish diet of about 2% of their body weight per day.

If you are adding too much fish food then your water quality can decrease as surplus nutrients build in the system and there’s not enough plants to filter the water. Conversely, not enough fish food and your plants won’t have enough nutrition. So know your fish weight!

The Knight, Until Spring 2017….


We started this system, “The Knight”, a bit too late in the year. It took a while for the bacterial colony to establish and there wasn’t enough time to achieve robust growth before the winter months. But we’ll be ready for the Spring!

Starting in Spring 2017, all Anacostia Aquaponics systems will have a specific goal for the year for fish weight and plant production based on each system’s characteristics. We will do our best to maximize production and quantify how much each system can produce.

Factors that will affect each systems’ goals include: system size and type; source water pH; access to light; owner preferences; and other environmental considerations.

(This system is named “The Knight” because it’s in a backyard across from Ballou High School in Anacostia, Washington DC. Their mascot is The Knights.)

Anacostia Aquaponics Partnership Program

Anacostia Aquaponics is in its “Partnership Program” phase. This means that we looking for partners who want to grow with aquaponics. We will design, construct, and help you produce with an aquaponics system for the cost of materials alone. This will be a two-way street, we will learn from eachother to improve the practice of aquaponics and expand aquaponics food production in DC.

Here is our brochure: Anacostia Aquaponics Partnership Program

Why are we doing this? 
Aquaponics is a highly efficient method of growing plants and fish in a symbiotic, recirculating, soil-less environment. It can grow significant quantities of food even in urban areas like Washington, DC. And aquaponics uses LESS THAN 10% of the water compared to traditional soil farming. If we are to meet the dietary needs of our rapidly growing urban population without ruining the environment, our economy, and our health, we will NEED to grow with efficient and local methods like aquaponics.

But aquaponics is hard work. It involves constructing and plumbing a water-tight recirculating system that requires an electric pump and aeration; and it involves balancing plants, fish, and water quality to achieve appropriate growth.

Despite these challenges, there are over a thousand aquaponics systems of many different types and sizes that are flourishing across the country, including many large scale commercial systems. (See examples in our brochure). And the University of the District of Columbia has several large systems in operation as well.

We need your help to work with us to improve the practice of aquaponics so that we can employ it to a level that our city begins to reap the environmental, economic, and health benefits of a better food system.

If you are interested in partnering with us to advance aquaponics in the DC metro area, please email We will send along more information and can set up a time to visit your site for a consultation.

Here is our brochure: Anacostia Aquaponics Partnership Program

New Aquaponic System in Anacostia

Carroll Bryant

Here’s a pic of Mr. Carroll Bryant, contemplating his forthcoming aquaponic system and drinking a tasty energy elixir. Carroll and his wife Janet have a 50 gallon fish pond. I met Janet at some Washington, DC DPR urban agriculture events and she wondered if it was possible to do aquaponics with their backyard fishpond….more to come!

UDC Aquaponics at East Cap Urban Farm

East Cap Urban Farm

The University of the District of Columbia (UDC) hosted a great event last week showcasing their large aquaponics system at the East Capitol Urban Farm in Washington, DC (across from Capitol Heights Metro station). This system is one of UDC’s “urban food hubs”, which are designed to “improve Food Security and Sustainability in DC neighborhoods through food production, food preparation, food distribution, and waste and water management”. UDC is planning a food hub in each of Washington, DC’s eight wards. Each hub will include aquaponics or hydroponics. Check out their urban ag website here.