Aquaponics (AP from now on) is a system to produce fish and vegetables in a closed loop system. It is not mentioned in permaculture books but I think AP has a place as part of a permaculture design. It is possible to incorporate the AP in a sustainable way in our designs too.
AP cannot be the main food producing system though. In an integrated food producing systems, it has a place with fish protein and vegetables. When done by the book, it can produce endless food and cover its costs in no time. It is also a good option to utilise dark corners of the land to situate the fish tank.
I am not going to get into the details of AP setup for the purposes of this article. I will explain the inputs and outputs to utilise them in a sustainable way. There are free PDFs on the net and forums if you want to get information on how to setup one.
The biggest part of the costs for an AP system are the fish food and fingerlings (after setup costs).
Fish food particularly easy to produce at home. First, you need to know your fish and what they eat. Usually trout, barramundi are carnivorous. They would eat:
• tenebrio molitor larvae (mealworms)
• hermetia illucens larvae (black soldier fly larvae)
• armadillidiidae (slaters, pill bugs)
• small fishes like gambusia affinis (mosquito fish)
These insects and fishes provide a complete diet. They are easy to cultivate at home for an endless supply of fish or chicken food (dual purpose).
For baby fishes (fingerlings):
• daphnia magna (water flea)
• turbatrix aceti (vinegar eel)
• mosquito larvae
For vegetarian fishes try duck weed or azolla. I boiled some silver beet, spinach etc. and fed to the fishes too. Green Algae also a good food source and high in omega 3s.
These would be sustainable options to produce at home. There are also recipes on the net if you are into making fish food from scratch in pellet or frozen form.
Another input is water but I guess there is no point of saying that you should and must use rain water in your AP system if you don’t want to fiddle with hydrochloric acid.
Fish sourced from lakes and rivers like carp and redfin also used in AP systems. Though, often it is illegal to transport live pest fish in Australia. I’ve heard from people that redfin purged in AP and grown a little more is a very tasty fish to enjoy in dinners.
Time stacking is also possible with AP. You can have bottom feeders like Tandanus Tandanus (eel tailed cat fish) and trout or perch at the same time. They grow to edible maturity in different times and cat fish also cleans the bottom.
The technology is advanced enough these days that reliable solar powered pumps are available to use in AP. As the pump needs to run 7/24, you might need to use a battery backed system as well.
Some people us a system called 15/45 that is 15 minutes run and 45 minutes off for the water pump. Oxygenation is also possible without an air pump using a simple venturi connected to your water pump. Though it may not be reliable especially for the trout. If you are going guerrilla and growing carp or redfin, venturi should be enough. A spare pump is also always advised as this is the heart of the system and failure of it can cost to you. There are battery powered, mains charged air pumps available too but used only for backup purposes.
AP outputs used for more than two purposes. Fish and veggies are the two main outputs of an AP system. You can sell or consume these. There is also the fertilizer output. This fertilizer collected in filters. You need to take these out of the AP system as they may clog the grow beds in time anyway. This fertilizer is best for fruit trees or wicking beds. Fish is a cold blooded animal. The faeces are ready to use in the garden without worrying about the pathogenic bacteria.
Water collected during the cleaning of the grow beds is also a good source of nutrients for the wicking beds. This muddy water either used for veggie garden or returned to AP after sitting in the settling tank for a while. You still have the bottom sludge which is a fertilizer for trees.
You can germinate any seed on the grow beds to use in soil veggie garden. We know how bio-intensive gardeners need seedlings all the time.
Once fish harvested, all the guts used in fish hydrolysate. That would be the best foliar fertilizer you can make at home. Make sure you have a second blender to blend the fish guts and heads if you want to keep your marriage intact :-).
You can incorporate the nutrition film technique (NFT) of hydroponics to utilise vertical spaces. NFT can grow strawberries away from the slugs and slaters using the AP water trickling down a 100mm pipe. Using vertical space gives you a lot of surface to grow food. This extra filtering allows you to hold more fish in the system too. Because you would be removing more of the nitrates from the water.
If you are a vegetarian, you can keep koi in your system and still enjoy the vegetables. If you grow a koi with blue colour on it, it may pay the entire setup cost in one go.
There are always ways to integrate systems in your design to achieve “abundance”. And the creativity comes in action to utilise the outputs in more than 2 ways. Observe and interact with nature and I am sure you will find the “edges” to utilise.