Backyard Aquaponics
A place to discuss aquaponics

Okay, Im a newbie to aquaponics and am in my first week of having a system, however I have years of mucking around with hydroponics,

My question is if aquaponics is self sustaining why do I see so many posts and enquiries about people feeding there fish with pellets and so forth


Thanks

Two reasons... inter-related

The volumes of water in most AP systems are small... far too small to provide enough succession of natural micro-organisms to feed the fish ... and to acheive faster growth rates than would occur naturally...

The limitation of water volume ... providing natural feed... would mean that we would only be able to stock at about 1/5 of the density that we do...

Thus AP, like RAS aquaculture or even pond based aquaculture... is considered an "intensive" system... rather than a dam situation with natural feed which is called "extensive"...

To acheive the higher stocking density... we have to supplement the feed... via pellets, or other supplements...

Secondly... becuase we can acheive higher stocking densities.... we create high wastes... which become... and sustain... our plant production...

A natural system can only support so much vegetation... becuase of the nutrient load... and it's usually only specific plants, more likely weeds... and usually nothing fruiting ....

Okay understand, so next question then, how does one know if the fish need food or are being overfed

Thanks

Condition monitoring of the fish.

Dead = not enough food
Fat = too much food.

Mostly they are fed until they want no more, a couple of times a day.

There are formulas that say at different ages and sizes fish need to be fed x percentage of their body weight. Sorry, I'm not gonna go weighing my fish often enough to keep track of that.

I just try to feed enough that they finish it all in about 10-15 minutes Fish get fed 2-3 times a day here.

If you feed too much there will be uneaten food left in the system to rot, this is not good.

If you don't feed enough, it depends on the fish as to if you need to worry about the fish eating eachother or if you will just have slow growth due to lack of food. In extreme cases, there might be some deaths due to starvation though most fish can survive quite well on little food as long as they are not too young.

As to sustainable. I suppose it might require understanding the definition of "self sustainable" of who ever told you that Aquaponics was able to be "Self Sustainable" without outside inputs. If you are going to expect a system to be completely self sustainable, without any outside inputs then I don't think you could take anything back out of the system either. If you expect to remove and eat fish and remove and eat the veggies, then you will have to put something back into the system to replace what you are taking out.

I would guess when people call Aquaponics sustainable, they are speaking of the fact that aquaponics uses far less water than most other growing methods and doesn't dump pollutants back into the water supply as well as the reduction of use of chemical herbicides, pesticides, and fertilizers. Also, since people can grow more of their own food right at home, it reduces food miles and in that way is also a sustainable practice.

I think TCL is spot on with this assessment

Maybe also other exchanges with the outside environment - if the system loses heat to the outside you have to add the energy to the fish, if the system exchanges gasses with the outside it must be balanced with inputs to the plants and animals in the system.

John

Okay that all makes sense.

I was informed by others and the place I bought the products "tank/piping/grow bed" that it is a self sustaining system, no additives or food required. That did not make sense, as even my son who is 15 said, but if it is self sustaining and everything is in balance what happens when you harvest 3-4 plants wont it be out of balance, same with adding or removing fish,

So in essence my understanding is now, thanks to you folks, is that the fish are beneficial to the plants and vise versa, there is a point were the volume of fish to plants will be in perfect balance and self sustaining but that balance is easily disrupted and requires adjustments of food for fish or food for plants. Also when one wants to maximise one side of the situation, be it plants or fish, then outside assistance is required hence the additional fish food.

Whew head spins

Wow... just out of curiousity... where did you get your gear, and who told you that...

Look at header at top of page

might of ment plant supliments once the system matures ?? Makes more scence to me

Could be, remember Im only new to this stuff.

I'd need a bucket full for the food to last even 5 minutes with my trout, 10 - 15 seconds is about what my guy's get. If I feed them much more than that the ammonia starts to rocket up. Currently my 30 trout are on two handfuls per feed.

1. We feed the fish a good quality feed as it helps to maintain the optimum health and growth of the fish.
2. The feed contains a good balance of nutrients and trace ellements that support the plants without the addition of extra supplements or nutrients. Just ask C1. Other people like to add chelated iron, eco-rose, seasol, maxi crop and rock dust,
3. Trout and Barramundi (Perth) require a high protein diet. Silver Perch are omnivores and will nibble at the algae on the side of the tank and plant roots that hang down in the water. You can also feed them worms, another addition to helping the self sustaining system. You can have gold fish and once again, if that is what you chose I believe they would survive without being fed. However the growth of the plants would not be as vigorous. The more food that goes in to a system the more the plants will grow. Just ask the keepers of trout.
We do run workshops once a month and you will get 2 hours of information and the opportunity to ask plenty of questions. We cover fish, plants, systems, maintenance, transporting and planting plus afternoon tea. The next one is this Saturday.
Hope this helps.
Faye

True in terms of AP alone. True in terms of any bio-system alone. But expand the term "self-sustainable" to the person doing the AP and he/she can include many bio-systems- on one farm - integrated - to create self-sustainability. AP is a valuable component.