Aquaculture video script (6m 4s)
The Principle for aquaculture is to raise healthy fish and plants.
What is aquaculture?
Aquaculture is the cultivation of aquatic plants and rearing of aquatic animals in a single, symbiotic growing system. It works like an automatic compost tea system, where oxygenated fish poo water provides essential nutrients for plants. Through this symbiotic relationship, aquaculture can grow more protein and more produce by area of land than any other growing system known to man.
In this chapter, we will talk about aquaculture in ponds, aquaponics in tanks and chinampas, the ancient growing system of highly-productive garden lakes.
Aquaculture in ponds
Here are a few things to consider when designing an aquaculture pond system:
Location
The pond should have plenty of shade to keep fish cool, and receive a continual supply of fresh water from rainwater collection or a series of off-contour swales, for example. Adding a drainage pipe directs overflow into another pond or swale system.
Size
If you have the option, it’s better to make many smaller ponds rather than one large pond.
Depth
A shallow shelf around the edge and deeper section allows space to grow plants near the edge and raise fish closer to the center. It should be a minimum of 30cm deep up to 2-3m, depending on the size of the pond.
Liner
Watch the earthworks video for a few options on pond liners. They range from clay, bentonite clay liner, plastic liner, ferro-cement among others.
Oxygen
Oxygenated water is essential for a healthy pond. To add oxygen to water, you can install a submersible pump that agitates and oxygenates the water or …add plants.
Adding pond plants
It’s easiest to take plants from a nearby pond, when adding plants to your pond. Most aquatic plants regenerate very quickly.
• Floating plants – Water hyacinth, frog’s bit, cattail, bog-mat, banana lily, spatterdock, arrow root, duckweed, water lettuce, Indian water chestnut, water spinach, water fern.
• Anchored plants – Morning glory, watercress, water chestnut, willow
• Emergent – Lotus, taro, wild rice, rice, bulrush, reeds, water chestnut, water spinach, cabomba, anacharia, hornwort, arrowhead, blue flag, baby’s tears, cattails, buttonbush, elderberry, golden canna, knotweeds
On the edge of the pond
Planting on the pond edge holds the soil in place and prevents erosion. Pond edges are fertile because they receive lots of water and nutrients. Here are examples of plants that grow well near a pond:
• Grasses like vetiver, citronella, lemongrass and napier give structure to the soil. Sweet potato, cassava, tomato and lettuce also grow well
• 1-2m from pond edge – Small fruit trees – Banana, citrus, papaya
• 2-3m from pond edge – Large fruit trees – Mulberry, guava and other legumes
Fish
Stocking 3 -5 fish per square meter is a good estimate when adding fish.
When introducing fish to your pond, first introduce herbivore fish, then about 3 months later add omnivore fish. Then another 3 months later, add carnivore fish. Otherwise, the carnivores will eat everyone before they can settle in.
Fish Food Recipes
Here are a few homemade fish food recipes:
1) Grow grains. Then harvest, process, grind and mix them with a high-pectin fruit, like mango, banana or crabapple. Then push it through a meat grinder to make a uniform strand. Dry the strand in the sun until it is crunchy. Cut into small pieces.
2) (Fish emulsion) – Another recipe is to fill a bucket full of dead fish and fill the bucket with water. Stir well and seal with a tight lid for 9 months. It will emulsify into a golden, sweet, thick paste, packed with nitrogen and other nutrients.
3) You can also feed fish legume leaves and seeds like moringa and peanuts, cooked foods like such as cassava, taro, sweet potato or insects, mice or termites.
Integrating fish with other animal systems
Chickens, goats, or pig house can be built on top of a pond so their feces falls straight into the water. Consider raising 5 chicken or 2 pigs or goats above a 5m x 5m pond.
Aquaponics
Aquaponics is an ecosystem that circulates fish wastewater through plant beds. It combines the best qualities of aquaculture and hydroponics without the need for chemical fertilizers or additional nutrients. Aquaponics is an urban version of aquaculture.
How do aquaponics work?
• Fish poop in the water
• Then you pump water into a trough filled with plants
• Plants consume the nutrients from the water
• Then, water returns to the fish tank
Food conversion ratio
This is the amount of food animals must consume in relation to their physical growth. These statistics shows how fish are one of the most efficient animals to raise:
Animal lb food : lbs growth
Fish 1½:1
Poultry 2:1
Pigs 4:1
Cattle 7:1
Sheep 8:1
Sizing your system
Recommended ratio of 1:1 – size of grow bed to fish tank – to start, move to 2:1 once you get it working.
Media and media depths
Make sure you use gravel without limestone or rinse gravel off the gravel by filling sandbags and dunking them in a stream. To see if gravel has limestone in it: put gravel in a cup of vinegar. If it fizzes, it has limestone and it will change the pH of the water. Or rinse the lime off the gravel by dunking it in a stream.
Fish tank
Look for 55-gallon oil drums, IBC liquid totes, aquariums, bathtubs or pond liners for good fish tanks. Go to www.gardenpool.org for other fish tank ideas.
Vertical aquaponics gardening
When growing your aquaponics garden, consider these unique vertical gardening styles: window gardens, PVC towers, zip grow towers, stacking towers. If using public water supply, run the water through your system for a few days to remove chlorine before adding fish.
Chinampas
Chinampas are polyculture systems built on raised beds surrounded by canals or swamplands. Chinampa systems have been practiced on saline lakes around Mexico, also Peru and Bolivia, for thousands of years. Chinampas can produce yields 2-3 times greater than flat land farming. Chinampas regulate the microclimate by retaining moisture through capillary action. Annual and perennial crops as well as cover crops and fruit trees grow well on chinampas.
Sizing chinampa beds
Chinampa beds can be any size but are commonly 2-4 m wide and 20-40 m long. The raised beds are 0.5-0.7 m above water level, with sides reinforced by branches, willow trees or bamboo.
Recap on this chapter
– By area, aquaculture is the most productive growing system on the planet
– Aquaponics is urban aquaculture and can be made anywhere
– Chinampas can produce 2-3 times more than flat land farming
Okay, this concludes the aquaculture. Thank you for your time.