Do I understand you correctly - you wish to raise fish to feed the chickens? What will you feed your fish? Is that cost going to be affordable/sustainable?
I raise fish and I can tell you it costs as much to raise my own fish as it does to buy it at the grocery store. On top of that there is the energy used to pump water. I keep my fish to demonstrate aquaponics, and find it fun, but it's difficult to say this is sustainable.
Hi in response to the stacking beds. I was also interested in that idea because it is all made of wood, but after visiting Growing Power last summer I changed my mind because the plants in their beds looked weak and they mostly grow water cress in a kind of stream that flows through the gravel. After using the IBC growing system and seeing how robust the plants can be there I am sticking with the single layer of wood beds that I plan to build as soon as the weather clears.
Vegetables need a lot of sun so the lower beds will be lacking in light. Also the upper beds are so high up it would be a pain to harvest.
I think is is just as easy to build a system with wood in a single layer and get many more veggies.
Also, have you thought about growing mealworms or black soldier fly larvae for your chickens. It is easy and cheap, I have grown both for several years and my chickens love them.
I agree with Bob on the cost to raise fish. Aquaponics is not necessarily a cost effective way to garden or grow fish, even if you are a do-it-yourself sort who is good at finding good deals. So far my experience has been (for my system anyway) that it is more suited to being an expensive hobby garden than really producing anything sufficient to replace the grocery store in terms of fish or produce.
With regard to Sacramento Perch, here is a link to the registered aquaculturists in California and the types of fish they sell: https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=3265&inline=.... Fresh Water Fish Company in Elk Grove is listed as selling Sacramento Perch.
If you are doing this to avoid fish meal from a sustainability standpoint, Sacramento Perch may not be the best choice since they are carnivorous and require fish feed that is high in protein which contains a lot of, you guessed it, fish meal. You wouldn't really be any more sustainable that way.
Omnivorous fish such as catfish, blue gill, or tilapia might be better choices...you could feed them an organic feed such as AqauOrganic sold by the Aquaponic Store, although it does contain corn. It also takes about a year to grow a fish to plate size (1.5 lb). I'm not sure how many chickens you have or how many pounds of fish meal you would need a month/year. Something to consider in sizing a system.
Also, as Bob pointed out, high quality fish food is expensive. Some people grow their own fish food (black soldier fly larvae, red worms, and duck weed), but you still have to supplement with fish feed since those food sources don't provide for all the nutrient requirements of the fish (think of duckweed as the equivalent of celery, and worms and larvae as the equivalent of chicken...if you were to eat only chicken and celery and nothing else you would have some nutrient deficiencies to deal with I think. Any nutrient deficiencies in your fish would be passed on to your chickens and plants, and then (assuming you plan to eat them) to you. Is high quality fish food cheaper than the fish meal you currently feed your chickens?
With regard to stacking beds, I have no experience myself, but I remember reading somewhere once that the lower beds do not get enough light unless they are rotated to the top. I would think that even if you could make it work, with the need for plumbing under the grow beds and room for the plants to grow to their natural height, that your lower grow bed would need to be pretty much sitting on the ground and the bottom of your upper bed would need to be up pretty high...5 ft or more maybe (?)...which would mean you would be up on a stool or ladder to do your gardening in your upper bed. Is there enough room in a hoop house for that? How to stack that much weight safely so that you can work on the lower bed without worry of getting crushed by the upper bed if it were to fall would also be a concern. (Think of the weight of the grow bed, plus the media, plus the water. A single grow bed, depending on size, can easily weigh 500+ pounds when full.) If you manage to figure all that out, I'd be curious to see how you accomplish it!!!!!!
If you are new to AP, you might want to start small and work your way up. Make sure it is something you enjoy, have time for, and makes sense for your situation before making any big investment in case it doesn't work out. If it does work out then you can always expand! Good luck!!
You should not under any circumstance feed leftover pieces from butchered chickens to your fish. Not only is it a huge contamination risk for the fish but also for any food you eat out of the system.
If you want to raise protein for the chickens, fish is not the way to go. Chickens do not normally eat fish; they forage for bugs and greens. The only reason they put fish meal in the chicken food is because its cheap protein. The healthy thing to do would to feed them what they are meant to eat. I would recommend www.backyardchickens.com as a great resource of information on chickens. They have a great fodder system (raising feed) that is very simple and uses regular water along with lots of forum members that grow/ raise food for their chickens. My opinion would be different if you were raising ducks or other water birds, but chickens are not that kind of bird.
You said there isn’t and probably never will be a perfect closed loop system and I disagree- it is possible! We use aquaponics to grow our food. The fish waste feeds the seeds that grow into our fruits and veggies. I harvest 95% and leave the rest to give me seed for next year (no need to buy more seed). The roots of the harvested plants go into the BSFL bin to produce BSFL for the chickens. The fruit and veggie peels from my kitchen go to the chickens, along with the corn, wheat and kale I grow specifically for the chickens. Chickens give us eggs and meat… We do use feed for the fish and the chickens but if we were forced off the grid we have a backup plan including plants and bugs for the fish and chickens (their natural food source anyway).
You stated you have a 24x20 space for your aquaponics so I would advise against stacking the beds. It is costly, more work to rotate crops and really only should be used if you don’t have the floor space. There are other growing techniques that may serve you better if you want to grow vertically, like grow towers! You have 480sqft of space and you could grow a ton (literally a TON of food in that much room using DWC).
Sacramento Perch were my first choice and I couldn’t find fingerlings when I started years ago. Should point out that Sac Perch would probably require some heating in the winter since you live in the foothills. I was looking about a month ago for a Sac Perch supplier and Fresh Water Fish Co in Elk Grove is no longer raising Sac Perch. I have not found a supplier in Northern CA including all the registered aquaculturists on the list. You also would need a permit from fish and game to have Sac Perch (if you could get them somehow) and they would prefer some small fish to supplement the pellet feed because they are protein lovers =). Have you looked into Rainbow Trout? They do not require heating in the winter, don’t need a permit to keep and they are quite tasty.
All the “hollering” about aquaponics you mentioned aside, I do believe it has its advantages- we are experiencing a drought season in California and Aquaponics uses 80-90% less water than conventional farming. It’s a way for me to provide fish for my family without checking the safe-seafood app on my cell phone every time I buy fish. It is a way for me to eat what I grow and I am still amazed I have bell peppers in February. It is right for me and my family and I hope you find a system that meets all your needs for your family and your feathered friends!
Our fish feed is 40% protein and that is the highest I have found. Since Sac Perch eat primarily what they can catch I would assume feeding as high of a protein as you can find would be good. They are highly opportunistic so they will probably do fine with whatever you choose.
Casey mentioned catfish, bluegill and tilapia. Catfish and bluegill are great for aquaponics, also easy to find fingerlings from local aquaculturists. Tilapia are not allowed in Northern CA and are not really suited for our climate anyway since they do not like water under 70*.