Type of fish for aquaponics?

Hi Sylvia,
I went to a workshop about aquaponics a few months ago. One of the most interesting questions was, "WHich fish to grow? On a previous workshop, they said tilapia was better for tropical areas, but I live in a mild temperate area. On this one, they were trying to figure out which one would lead to happy fish and great plant growth for the given temperatures. They said trout like cold temperatures, but plants dont' grow much in that range. Do you have a range of fish for different climates?
Thanks,
John S
PDX OR

I've often wondered about which fish too. I have a few tilapia in my catchment tank that I use for garden irrigation, along with some mosquito fish. I'm told that it is too cool where I am for the tilapia to reproduce. But the fish have slowly been growing ok. It's just slow.

I was wondering what fish would be better in a cool tropical setting. Guppies do great on my farm and readily reproduce, but they are rather tiny. I'd like something more edible. Perhaps some species of catfish? Or something else?

There are lots of options for fish in an AP system, depending on what your goals are. Tilapia are great because they are super hardy, in the right environment, they grow fast, will reproduce readily in captivity, and the temperature that they thrive in is a perfect temperature for both the nitrifying bacteria, and many of the veggies that we like to grow in aquaponics. We love them for our indoor systems. But the problem, as you've pointed out, John, is that they are tropical and won't survive colder temps. Trout have the opposite problem - they can be tough to grow in places where the summer gets hot. Plus they require a ton of oxygen and a current, which can be stressful if you experience regular power outages. Many of your native North American fish, however, will thrive at the same temps as tilapia (mid 70's to low 80's) but will survive into much lower temps. These are your catfish, blue gill, striped bass, etc. The best thing to do if you are in an outdoor, greenhouse setup is see what is growing at your local hatcheries, and go talk to them about the best fish for your particular location.

My greenhouse system is new but has many happy goldfish and fathead minnows in there for now. I got them for $0.12 each at the local pet store.

I have seen videos on YouTube of goldfish swimming under ice in subzero weather. I have seen videos of them swimming happily in 90deg F water as well. Mine have seen lower 40s to lower 70s so far.

They are omnivorous. They grow to about 14" long max and are in the carp family. So they have scales and are a tougher fish. I just plain want something tough and cheap so I can focus on growing veggies for now as I start up. They look like small Koi when they get big so they are beautiful.

Koi. They are also just fancy carp. They sell for $15ea at 6" long at the local pet store. You can get fingerling discards for free from most Koi breeders that literally just kill the ones they don't want. Then sell them in 6mo-1yr to the local pet store/online at a great price. Should be better return on investment than selling meat fish for profit. 1ft long Koi go for $100 I hear. Check it out.

I am likely to work my way towards trying hybrid bluegill and catfish at some point for personal consumption. They put on some really good weight and can handle our environment.

If you use trout I have seen a great way to create current while simultaneously adding oxygen to the water. Just take an aquarium air pump with air stone and insert it into a piece of PVC pipe with a 90deg elbow up top and the air stone on the bottom. Place the PVC pipe entirely under water and attach to the inside of tank. As the air bubbles move up they push out a jet of water to create current. Most fish seem to love some sort of light current. Channel Cats do too I hear. You can get DC/battery backup air pumps online at Amazon.

Marty

Hi John,

We've grown rainbow trout in our aquaponic systems before and they do fine. They are actually my favourite fish, as they will grow from tiddler to plate size in 6 months and taste great with butter / garlic
I live in a warmer climate, and put the trout fingerlings in the tank in Autumn, ready for harvest by the beginning of summer. The trout die off in summer in our heat, but if you are in a temperate climate you could have fresh trout all year!

If you are growing plants already, then adding fish is no issue. Just add whatever your local stockist has, as they will be suited to your climate.

If you are worried about plant growth though, try putting your system in a greenhouse. The fish will do fine with the warmer temps, and the plants will like it. Trout will start to suffer at about 80'F (30'C), but you can prolong their season by chilling the water (which wont be an issue if you are in a temperate climate).

We have mixed freshwater crayfish and fish, it doesn't work. The marron will come out at night and eat the fish, shredding their tails to bits and leaving the fish scarred. In the wild the fish can go to deeper water, but in a tank they just become marron bait. Just incase you were thinking of mixing the two, best to have separate tanks.

Cheers,
Mel