Backyard Aquaponics
A place to discuss aquaponics

There's a book entitled "You are what your food eats". I haven't read the book, but even the title is something to consider.

When I read up on aquaponics, I wonder about the push for maximum growth rates. That same mentality brought us industrial meat production. Grain-fed beef isn't nearly the same quality as grass-fed, nutritionally. The lipid profile of grass-fed, pastured beef is far superior to that of corn/soy-fed CAFO-raised beef.

I understand that many AP farmers use organic feed that is often GMO and corn/soy free, but that raises the input costs considerably.

I just looked up the nutritional profiles for 6 of the most commonly farmed species in AP: tilapia, carp, catfish, trout, perch, and sea bass (barramundi in AUS), and they can vary quite a bit between species. I also wonder how much it might vary between individuals of the same species depending on environmental factors, including growth rate, feed, water temp, etc...

The cold-water fish tend to develop a lot of their poly-unsaturated fats as Omega-3, rather than Omega-6, Tilapia and Catfish, as warm-water fish, tend toward Omega-6.

IF all you want is maximum animal protein in the shortest possible time, then I suppose feeding them for maximum growth is the way to go. Personally, half the reason of eating fish, to me, is in getting the Omega-3 fatty acids. Perch and Sea Bass have the highest ratios of n3:n6, but Trout has the highest actual total of n3 per serving, and a respectable 6:1 ratio.

Most of us are limited by what we can buy from the feed places, there aren't that many options out there.

If I had the options of getting a feed that's got higher rates of corn/soy, that the fish would take, I'd do it in a heartbeat. It's better then the drenching of the ocean floor for anything organic that'll be ground up into fish meal.

It's also been said on here a fair few times not to overfeed the fish, any excess food that's turned into fat is just wasted food.

And on the beef argument, the other side is that grain fed animals grow quicker, and get to slaughter size quicker. A grass fed cow will produce far more greenhouse gasses than one fed on grains, and they'll be alive for longer. The average cow can produce more greenhouse gasses than a mid sized family car.

You can't just look at it on a per-cow basis. These calculations fail to take into account the entire system: how healthy grasslands need ruminants like cows to thrive. How much carbon is sequestered in the sod of a healthy prairie? When we bust sod, destroy healthy soil, oxidize the carbon in the humus, just to grow corn/soy, using fossil-fuel fertilizers, the calculations don't add up.

It's all good saying don't eat it, only grass fed beef.

But the simple fact is that we don't have enough grasslands to support the amount of beef that is in demand, and that demand is only going up with China and other developing countries eating more meat. Already there is 1/3 of the surface area of the planet devoted to raising livestock, and you can have more livestock living off a harvested field of corn, then a field of grass. The planet simply doesn't have the resources to grow all that livestock off grass.

I agree that cows just fed on grass is better for the environment, the dung creates fertilizer, and it's happily been that way for millions of years. But it's not realistic for the current demand, and certainly not realistic for the future when demand will increase.

Also, the amount of ground that's suitable for just grass is limited, you can take arid regions, tap into an underground river, and pump that water to the surface, to grow wide fields of corn/soy, where grasses wouldn't naturally grow.

The answer to all this however is simple, if everybody ate less meat, and more grains, then we'd be able to sustain and the livestock on just grass, but telling somebody they shouldn't eat that 500g rib-eye steak won't happen.