Backyard Aquaponics
A place to discuss aquaponics

Hello,

I have been working on an Aquaponics system for a few months now and this question has been in the back of my mind for some time.

From what I understand, Aquaponicists consider fish an essential part of the process. But what exactly is it that fish do for the system? All the nutrients that are going to the plants is coming from the flakes as far as I am aware. Do fish contribute any nutrients of their own through this process?

Also, I know that ammonia is necessary for the beneficial bacteria. But I have also heard that a build up of food particles and such at the bottom of the tank can create ammonia through decomposition. If stirred every once in a while to prevent things like mold from developing, could just sprinkling some food over time and letting it break down be a decent replacement to fish? All the ammonia production without the diseases and fungal issues that seems to be so prevalent in fish in the town's water.

If someone could either identify what exactly I'm missing in the benefit of fish that will never be consumed for a simple nutrient based aquaponics system (Although, this would lean more Hydroponic than aquaponic in this situation) or issues that may arise from creating essentially a sump containing a nutrient and ammonia load?

Thanks!

Basically the fish are providing an amm source to feed the beneficial bacteria. The amm from fish is either from excretion or through respiration across the gills. The aquaculture feed also has trace nutrients and goodies to promote fish and plant health. The fish waste solids can also end up in the GB where they can be further broken down by worms to provide further nutrient.

Fish are not required to grow plants and any amm source will feed the beneficial bacteria, like, urine, charlie carp, decomposing feed, urea etc etc.. but all these options arent really aquaponics. Aquaponics is using fish to grow plants and vegatables.

The reason we use fish to grow plants and veg is very simple... its a win/win. We are growing fish while we are growing veg and we can eat both. Using any other amm source is really cutting yourself short in my opinion.

If aquaponisists are growing/using unedible fish to grow plants there could be 2 reasons. Firstly is they are not interested in eating the fish but would like something colourful to look at and show there friends whilst using them to grow veg. Or secondly, they are using plants to control the nitrate production for their aquarium instead of wasting water and cleaning filters. Once again, a win/win.

Obviously there are a few other reasons people opt for fish at home like wow effect and something cool to show friends.

To me the benefit of the fish goes beyond just a source of nutrients, as Charlie said you can use several kinds of non-living things for it. Part is the joy you get from pets, and I think there is a dynamism or animism that is added with the fish swimming and being themselves. Just looking at plants is fun, but they move very slowly. Add fish (and moving water) and it is a lot more interesting.

Hi Merkaba, as everyone is different we all want different things. My aim was to be able to grow as much food for my family of 5 as I can on our property and to reduce my need to buy and go to the supemarket. I really don't like shopping very much and I can't stand to see inferior produce at high prices. I get a lot of satisfaction from harvesting and presenting a meal grown at home. When I saw Joel on tv back in 2006 I knew and said instantly "that is the way to go". To be able to add a protein source such as fish to my property, then the water efficiency, plus the ease of raised beds and not only the wow factor of growing Barra in the backyard, the interaction of the fish, especially trout is fun.
It really is easy gardening and I think it ticks all the boxes, I never stop learning and still enjoy it after 6 years. I have a freezer full of fish and beds ful of herbs and veges. Even the goldfish here at the shop are a pleasure to feed and are a joy to keep. It is nature at its best.

Thanks for the responses so far. The main issue that I've been encountering with fish is that the tap water here seems to be carrying a number of issues with it and causing stress such as high hardness, chlorine/chloramine, occasional spores from the water lines (which has manifested as cotton wool disease in my tank at the moment). I have already tried a number of different treatments for all these issues such as cutting the water with distilled water to reduce hardness, using water conditioner for aquariums, all in one fungal/clamped fins/ich/ etc treatments. And the gist of this whole idea of using decaying feed in order to provide a nutrient load and an ammonia load like an aquatic version of a compost bin to overcome the water conditions.

Now, I've mentioned mold as one thing that may emerge from the aquatic compost bin. Is there anything else in particular that I should keep an eye on to make sure my plants aren't succumbing to disease or fungi in this method?

(maybe when I move out of this town in a few years, I'll look into traditional aquaponics)

You may need to filter the water somehow if it's causing that many issues... or build a still and make your own distilled water. Or water collection depending on what type of roof you have.

If water quality issues are that significant for you, Merkaba, you may want to look into one of two upgrades to potentially make your water that much better. A simple "whole house" filter, which would be a single filtration unit and relatively inexpensive - probably under $50 and relatively easy to install if you have basic plumbing skills. The other option would be a more complex, but still fairly easy to install, system like a multi-stage reverse osmosis filtration system. The upside to the installation of either is that the over all quality of your water will improve which means better water for the humans as well as fish...

For RO systems, and some of the more specialized pieces of equipment for AP (Uniseals, etc.) one of the better sources I've found in the US, so far, is BulkReefSupply.com. If you have any in your area, you may also want to check out local hydroponic stores as well. While the nutrient components of hydroponics may not easily lend themselves to AP, much of the equipment is identical.

TCLynx mentioned awhile ago that we could distinguish systems that like to have living biofiltration as bioponics, versus hydroponics where you want things sterilized. There may be several interesting ways to still do bioponics but without fish - peeponics would be an obvious option for you.

If you want to eat the produce from the system you should stay away from conventional aquarium remedies for disease and water conditioning products.

Actually-- if you read a number of the sagas of folk filtering and growing plants before they add fish... you'll find that you can get production, and... by the nature of filtering with plant material... you are indeed pulling nasties out of your water.

If you grow some 'inedible' material for the first couple of cycles... or simply discard, rather than eat the first production cycles... plants actually do pull the heavy metals and such out of the water...

Have you noticed the use of 'duck weed' as a feed plant for the tilapia? A reservoir of of water filtered by the duck weed-- that didn't go to feed the fish-- could ultimately 'filter' the water... That reservoir could then become your water 'replenishment' source... you will have to replenish.

City water filtration here (we do have heavy metal-- a rocket fuel production plant... and dreadful water recycling... our 'reservoir' is essentially an open sewer... we treat the sewerage, but then the water travels down a long wash, full of native plant material. It makes a difference.) uses layers of specific materials... carbon, for one, but then it also utilizes a series of different sized sands- one they label 'ruby'... (said to pull heavy metals.) but I have no references other than attending a seminar when I was a member of a 'water purification' unit for our Army Reserve.

Usually, if there is a 'water purification' company active around you... they will have test kits for heavy metals. See if you can get a rep to your household ... and test all your 'water' as a comparison.