If the following question is already answered in a post please direct me to it. Thanks

I have an existing koi pond with some relatively attractive koi but I have no interest in watching fish swim about (I'd rather be gardening). I would like to add an edible fish to the mix but know that there are many hurdles. The pond itself is concrete, a 12 foot long tear drop with a shallow end that has a ridge between it and the 'deeper end" but when the water level is high enough the fish can access both sections. The deepest section is 4-5ft, currently there are water lilies and some type of "grass". I just dug everything out and put back just enough to 'restock' the pond because it had grown completely over. We have a pump that filters through a washable medium and pumps to the shallow end (moveable hose). That's the basic format, I'll include pictures tomorrow for anyone interested in helping or hearing about it.

My goals are to include edible fish (I'm in zone 6b VA) that I can either raise on home grown grain alfalfa etc (suggestions please). I have no interest in feeding industrial feed (I don't want it in my body either). I cannot currently adapt to using grey water but will in the future so for now its a closed loop. So far I've come up with the creating a new side area that will drain into the existing pond, using the pump to pump water into gravel with growing medium above it and use that area for water loving veggies (suggestions). I don't know how else to "clean the water. That water then needs to fall to aerate for the fish so it should be elevated.

Thoughts, concerns, ideas, links to this scenario being addressed previously? Thanks

Very interested in this project as I'd like to do something similar, though I keep going back and forth between wanting to include edible fish and just having a frog pond (no fish at all) with edible pond plants. I'm currently growing some edible water plants in my aquaponics system; Duck Potato, Cattail, Pickerel Rush, Tiger Nuts, American Lotus, Egyptian Lotus, Watercress. So far have not had great success with regular veggies except Chard in a flood and drain bed.

I've never tried the flood and drain either, looking forward to it though. I'm wondering if there is an easy way to do this with the existing pump and no further wiring/timers etc.

The flood and drain tank has to be elevated above the fish tank (pond) or sump tank, but otherwise it's very easy to do with a Bell Siphon which you can make (hey, if I can make one, anyone can!).

http://affnan-aquaponics.blogspot.com/2010/05/siphon-revised.html

What does a bell siphon do and how would it benefit over the existing pump. Thanks for helping

Tilapia is the only fish species I know of that works well in small tanks, but dies when the water temp falls below about 52. They grow relatively fast, and if fed well enough, the fry grow to harvestable size by the end of one growing season. People who raise tilapia usually have some tanks in green houses where they keep the breeder fish over the winter. They lay eggs in the tanks and those hatched fry are set out in the pond in spring when the water is warm enough. You have to be pretty far south. I know of operations in south Texas and Florida. I've heard of using channel catfish, which are more tolerant of cold water, but they need fairly large tanks or ponds. Can you or would you want to build a green house over your pond?

Bluegill will grow large in a small tank, but are insect-eaters so more difficult to feed. I have a few (I think) still surviving in my aquaponics. People say Channel Catfish are easy to keep but I managed to kill all of mine.

The Bell Siphon allows the flood and drain tank to fill up and then suddenly drain. Water is pumped into the tank until the level of the water activates the siphon, draining the tank. It's pretty cool, actually....

People are helpful on this messageboard: http://backyardaquaponics.com/forum/index.php

are you currently feeding the koi or letting them scavenge what algae and plants they can eat? Reason I ask is that there is a thread on the forum here advocating that carp really aren't all that bad a fish for eating... if I recall, the post mentioned that they could be pressure canned like tuna fish and the bones pretty much dissolved and it tasted similar to tuna fish. it's stuck in my head for some reason.

anyway, you already have the koi and it sounds like they are doing fine in your system and climate. adding some more regular goldfish each spring and harvesting that fall or the next, depending on growth rates, may work just fine with no modifications.

I would probably want to cool and clean the water through a wetlands area or two before having it enter a pond that contains animal life of any kind. If you have the room set up a couple of wetland filters that you can direct the greywater through before going into the ponds.

The koi are self supporting, imao though they are far too tiny to eat. I wonder how much any fish is capable of growing in this closed loop environment. I'd be open to feeding the fish if I could grow the food myself.

btw, I do not have a grey water setup running as of yet. I occasionally drain a few rain barrels into the pond to refill it if the rains aren't doing so. My plan is to eventually setup the grey water but its going to be a number of years until that is possible. For now I envision building uphill from the pond, installing some reed grasses into a gravel area and possible leaving room for growing (with massive suggestions from this group on how to construct an area of this type to grow veggies, the bell siphon idea is a great start but I wonder if it overcomplicates the system.).

I do have a greenhouse that I could use to overwinter breeding stock for the coming spring, would a barrel and an aerator pump, maybe a few lilies for cleanup work? I'm trying to move everything towards Fukuoka's advice of simplifying everything so I'd like to approach any changes to this system with that in the forefront.

I would not include greywater in a small system which is also meant to support fish, it may be too difficult to keep the water fresh. If greywater is used it should be thoroughly filtered through a wetland as Brenda suggests, in my opinion. But I think including it at all is looking for trouble unless you're already expert at aquaponics/pond systems.

Carnivorous fish can eat Red Wigglers, Crickets, Black Soldier Fly larvae, etc raised for that purpose.

David - if the koi are currently self-supporting on their food, it sounds like you have a pretty ideal setup for starting up a small aquaponics trial. If you can set up a basin/trough with some growing media to start some plants above the level of the pond as you mentioned in the OP, you could let the water run down through your current filter before returning to the pond until you are comfortable that the plant bed is purifying the water sufficiently.

Aeration through an airstone/airlift or just cascading through a fine rose when returning to the pond may also help your fish increase their size. Koi can reach sizes up to 2 feet in a pretty reasonable amount of time. A 12 foot long pond that is 4-5 feet deep at one end should have at least several hundred gallons. With good aeration, filtration and supplemental feed, quite a few pounds of some kind of fish can be raised per year.

There are several free documents that can be found by searching for low tech aquaculture that describe ways of feeding omnivorous fish, such as carp. Everything from cut grass to manure is used to increase the nutrient density in the water to support fish growth.