A Community and Forum For Aquaponic Gardeners

My early stage plans

Hello everyone,

I'm considering setting up an aquaponics system in my existing greenhouse, which was built on top of the 10'x10' slab that used to be my back patio. I need advice picking a fish, so I came here. Let me tell you a little about the space.

This greenhouse is not very well insulated, but it stays warmer than the outdoors, and in the summer time, the windows can all be opened to ventilate. I have two metal shelving units in there right now that are just being used to store stuff (such as Perlite that my husband wanted to use to grow oyster mushrooms), as well as a bunch of gardening tools and a deep freezer that will most likely have to be moved. That is because my idea is to get a used hot tub (there are plenty of them available for free around here) and put it in the greenhouse to use as my tank. I imagine the tub will probably hold about 300 gallons, but since I don't have a specific tub in mind, I'm not sure of the real capacity. Another piece of information is that I live in Portland, Oregon. We don't get very much sunlight most of the year and the average annual temperature is about 45. The greenhouse does get pretty warm for a few weeks out of the summer, depending on the year. Seems like this year (and last year), we've had no warmth at all.

Another issue is that not having done this before, I have no idea what temperatures of water I might see. My husband says that a small tank like that will stay pretty warm. There's also the option of actually running the hot tub's heater (even though I don't want to have to use energy inputs in my system) on a low setting if need be. Is there a way to estimate the temperature my water will be based on the tank size, average sunlight, and such?

Is there a fish that is tasty and can tolerate temperatures in both Portland's mild but cool winter and its mild but cool summer?

Last week, I wanted to taste the perennial aquaponics favorite, Tilapia, because I wasn't aware of ever having eaten it before. I have to say, I hated it. It tasted fishy and somehow dirty, and the texture was really too firm for my liking. I don't see myself ever growing Tilapia now, so I need another option. My other thought was trout, but I don't want to be stuck to the cold-loving plants, and I don't want to have to start fresh with new fish every year. It seems like most people who grow trout talk about starting over and I'm not sure why they do that, but that doesn't appeal to me at all. Also, I definitely want edible fish. I'm not opposed to having a few ornamentals in there, but this is for food purposes.

I'm also considering using numerous species in the tank, such as freshwater prawns and crayfish. Maybe even some bivalves if I can find a good freshwater one that doesn't have to be kept too cold. Any advice on that? And on that note, I found a site talking about some Australian freshwater lobster-like shellfish called yabbies. What's the legality on raising something like that in a closed system with no chance of escape, like mine? I'd be open to raising catfish, but I don't want to have a floor that is too crowded, and I think I'd prefer shrimp and crayfish to catfish, if I have to pick.

I know this was long, so I appreciate it if you read this far, and I appreciate your input even more!

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Permalink Reply by Sylvia Bernstein on August 10, 2011 at 6:57am

Hi Christine. I love that you are giving so much thought to the fish in your system! I have a few thoughts, and I'm sure that others in this very active community will chime in as well.

First, you would be well served to contact several local hatcheries and find out what fish is readily grown in your area. Not will this help you understand better what thrives in your cooler climate, but you might also be lucky enough to uncover a source of inexpensive local fingerlings who don't come with a hefty shipping cost.

Second, I wanted to jump to the defense of the poor tilapia! What you had was undoubtedly imported from China, because approximately 90% of the tilapia in this country is. They have probably not been raised in optimal conditions, nor where they purged before harvesting, and they were frozen for some period of time. After a few years of aquaponics I finally got up the moxi to harvest my first tilapia recently (you can read about it in this harvesting tilapia blog post) and I couldn't believe how good they tasted! My friend who helped me with the process took a couple home and he aptly described the difference between these fresh fillets and the typical frozen, Chinese stuff as severe as the difference between store bought tomatoes and garden fresh tomatoes. I have to agree.

Aquaponic gardeners gravitate to tilapia because they are fast growing...and easy. I've also grown koi, goldfish, trout and catfish and I have to say that the tilapia are definitely the most forgiving of my various and inevitable system issues.

All that said, you have a lot of great choices you are exploring so I"m sure you will find something you are excited about raising!

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Permalink Reply by TCLynx on August 10, 2011 at 7:24am

Yea, sounds like the tilapia you tried were not so good. Now I'm not a big supporter of raising tilapia but a fresh tilapia out of an aquaponics system that is caught, quickly killed and cleaned then either frozen or cooked is not what I would call "fishy" They are so incredibly mild that you can disguise their taste with just about anything. Much like catfish. If overcooked tilapia can become a bit firm to stringy even in texture.

However, knowing you are in a cool mild climate, I wouldn't really recommend tilapia except maybe for your initial cycle up since they are such tough fish. I would probably recommend Blue gill for you if they are easily available. Harvest size range for blue gill will probably be similar to Tilapia, maybe a bit smaller but with your climate I would guess similar without heating. Blue gill are slower growers but if your goal is more for the gardening with an occasional fish to eat they could be perfect for you. Catfish are also good but I like bigger tanks for them usually though they will grow slower for you with cooler water.

Keep in mind you need quite a lot of plant growing space to support a 300 gallon fish tank. You really don't need a huge number of fish to provide nutrients for the plants if you don't have a huge amount of sun to help you use up those nutrients in the plants.

Just because you grow trout won't necessarily mean you can only grow cold weather crops, the trout just can't take hot water. The plants would actually prefer the water be a little cooler than the tilapia would want it.

You will have to look into the details of different exotic species in Oregon since it tends to vary by state.