Fish farming is aquaculture. Soil-less farming of plants is hydroponics. Combine the two and you come up with aquaponics.

Take a look into an aquaponcs set up:

 

Recycling of food for use by plants and fish 

Stock the fish first so they produce food for the plant. That plant food actually comprises of poop of the fish and some extra feeds in the form of pellets in case pellets are provided. You can use duckweed and azolla as fish food. In that case, you will have to grow them ahead of stocking fish.

Fish poop or extra or unconsumed pellets produce ammonia. The water containing ammonia will be pumped to the grow bed. There, bacteria nitrosomonas will feed on the ammonia and turn it into nitrite. The bacteria nitrobacter and nitrospira will feed on nitrite and turn it into nitrate. This is the form of nitrogen that the plants will absorb and use as food.

In this set up, the grow bed is above the fish tank.

You can have a set up where the fish tank and grow bed are beside each other.

The space can be the same as the garage of a compact car.

An aquaponics set up in one garage space can support a family of four. Two set ups can give extra income, that one family member can devote his time to aquaponics. In short he or she is gainfully employed by two aquaponics set ups.

Snap solution A: pH at 6.4; P₂O₅ gives phosphorus at 0.13%; K₂O gives potassium at 0.04%; calcium at 0.06%; magnesium at 0.01%. Mix these ingredients in one solution of one liter tap water.

Snap solution B: SO₄ gives sulfur at 0.28 ppm; iron at 63 ppm; zinc at 19 ppm; copper (trace); and manganese at 19 ppm. Ppm means parts per million. Like in solution A, mix these ingredients in one solution of one liter tap water.

You notice that nitrogen is missing in this snap solution. The reason is that nitrogen is provided by fish poop and unconsumed feeds.

The growing medium consists of 10 liters tap water added with 75 milliliter (mL) of solution A and 75 mL of solution B. Pour this medium into one hole or container where one kangkong seedling is grown. You may pour all 10 liters at once or stagger pouring according to the capacity of the container.

Formulated snap solution for plants. You will need to supplement the food with snap solution because the fish poop and unconsumed feed give nitrogen (nitrate) only. Plants need more nutrients. This snap solution was formulated by the Institute of Plant Breeding of the College of Agriculture of the University of the Philippines Los Baños, located in Los Baños, Laguna, Philippines. Snap solution is as follows:

Snap solution A: pH at 6.4; P₂O₅ gives phosphorus at 0.13%; K₂O gives potassium at 0.04%; calcium at 0.06%; magnesium at 0.01%. Mix these ingredients in one solution of one liter tap water.

Snap solution B: SO₄ gives sulfur at 0.28 ppm; iron at 63 ppm; zinc at 19 ppm; copper (trace); and manganese at 19 ppm. Ppm means parts per million. Like in solution A, mix these ingredients in one solution of one liter tap water.

You notice that nitrogen is missing in this snap solution. The reason is that nitrogen is provided by fish poop and unconsumed feeds.

The growing medium consists of 10 liters tap water added with 75 milliliter (mL) of solution A and 75 mL of solution B. Pour this medium into one hole or container where one kangkong seedling is grown.

Germination and transplanting

Kangkong seeds are scattered uniformly and thinly in a sowing tray filled with about four inches thick garden soil and watered using ground water. After seven days, prick the seedlings and place them in a seedling tray containing garden soil. Transplant seedlings in styropropylene growing boxes 14 days after pricking..

You may do the same for tomato, eggplant, lettuce, pepper, amaranth (hybrid).

Protect against mosquito larvae in grow beds. This can be done by growing some fish in the grow beds that will feed on the larvae. Be sure to make an opening where fish can surface and breathe to get supplemental oxygen.

Water. As much as possible avoid using tap water because this is chlorinated that can harm the fish and the plants. Use water from a deep well or shallow well, or rainwater.

If your only source is tap water from the pipes, allow it to stand in open container for 24 hours before using.

If you use rainwater, be sure that it is not contaminated by smoke from a coal plant, or chimney.

Do not allow the water level in the fish tank to go down. Water level in the grow bed would also do down.

Fish stocking rate. For tilapia, 77 pieces per square meter. For other species, ask the vendor or a pet shop owner.

Temperature. Don’t allow temperature in grow bed and fish tank water to rise above normal.  That is at least 75 degrees Fahrenheit, if you grow tilapia.

Dissolved oxygen in fish tank. It must be 5%.

In raising tilapia (or any other fish species) in a drum you may need an aerator. However, in larger fish tanks you you need and aerator.

In 21 days you can harvest kangkong.