In a former life, before moving to the Ozarks to embark upon an unanticipated homesteading lifestyle, I studied to be and worked as a zoologist and marine biologist. As odd as it may seem, the skills I acquired and the things I learned in that life are not as far removed from a farm in the middle of the country as you might think. As it turns out, adding fish production to a self-sufficiency plan is as feasible as it is beneficial.
I won’t rehash the health benefits of fresh fish in the diet. I will, however, state that having an additional protein source and adding variety to your diet has wonderful psychological benefits. The ability to provide variety in your diet cannot be overestimated.
When it comes to raising fish, about the easiest species to work with is the humble (yet delicious!) tilapia. Tilapia are tolerant to a wide range of water quality parameters, they eat a lot of stuff that is considered undesirable in many aquaculture settings, and they grow like weeds and reproduce like rabbits. The hardest part of keeping tilapia is maintaining water temperature through the cold months, but with a bit of ingenuity even this obstacle is not insurmountable.
Tilapias are filter feeders, and they are generally plankton and detritus feeders. In other words, they eat all the funky stuff that is suspended in the water column. They can be raised on almost any commercial fish feed, and can even eat things like dog and cat food. Allowing algae and other aquatic plants to grow in a tank, often a big no-no in other aquaculture endeavors, can provide a free source of supplemental feed for your tilapia. When I was in graduate school, some other students and I were tasked with cleaning out some large fish tanks that had been sitting untended for several years on one of the school’s docks. When we drained the murky green algae choked water from the tank, we found a fair number of large tilapia, along with juveniles, thriving in the gloom. These fish had lived for several years, forgotten by the professor or grad student who had been using them in their research, living only on the algae that grew naturally in the tank. I don’t advocate this strategy in fish farming; I only bring it up to illustrate what a hardy species tilapia are.
Tilapia don’t require heavily aerated water. They have the ability to gulp air at the surface should water become anoxic. Again, I am not advocating growing fish in oxygen-poor water, but pointing out that aeration need not be extreme. Allowing water to fall back into the tank on its return from your filtration system will input quite a bit of oxygen, and should adequately supply your fish.
Setting up an aquaculture unit can be done with readily available supplies. Easy set pools, available at end of season clearance sales at the local Walmart, make great fish tanks. An 8 foot pool with three feet of depth holds a bit over 1,000 gallons. This is enough volume to comfortably raise 250 fish to a terminal live weight of 2 pounds. A two pound fish will provide two ¾ pound fillets. The uneaten portions of the fish make great fertilizer, as fish meal or fish emulsion.
A simple biological filter system can be built using a 25 gallon trough, a five gallon bucket, and some gravel. Drill a bunch of ¼ inch holes in the bucket up to about 6 inches from the bottom. Place the bucket in the center of the trough, weighted with a brick. Fill the space between the bucket and the trough wall with gravel, almost to the top. The gravel will provide substrate for bacteria that eat the waste products produced by your fish. The bucket will house a water pump, and the holes at the bottom of the bucket ensure that all water going through the pump is first drawn through the bacteria rich gravel.
Now all you need is a bit of plumbing to allow water to flow out of your tank, into your filter, and back into the tank. I always set up systems with an overflow from tank to filter, and pump water from the filter into the tank, with this configuration a broken pipe will never cause a tank to be pumped dry which has a tendency to kill your fish. Set up a stand pipe at your chosen water depth and allow water to flow from the tank into the gravel of your filter from this pipe. Pump water from the center of the bucket in the filter back to the tank, allowing the water to fall some distance into the tank. This fall will serve to aerate the water. A 400-500 gph pump will give your water plenty of turnover and aeration
As I said earlier, water temperature is the biggest hurdle in raising tilapia. In order to achieve optimum growth rates water temperature must be in the mid-70s or higher. Some strains can survive in water as cold as 48 degrees, but they don’t grow at this temperature. We combat this in the winter months by keeping our tank inside our high tunnel. Supplemental heat is provided with large aquarium heaters. This has a twofold benefit: first the water maintains a temperature conducive to fish growth and second the water provides a great thermal mass that helps keep the tunnel warmer. Win/win.
A friend of mine set up a barrel stove with stainless steel water coils inside to heat his fish water. Never use copper pipe for aquaculture, copper can be toxic. This friend used stainless gas line for his coils and it worked great. You can get a two barrel stove kit and run your water heating coils in the upper barrel. This one is still on my projects list. I like it because it doesn’t require electricity.
Stock can be had from a wide range of sources. The closer to home you get your stock, the better suited it will be to your environment. Once you get your initial stock you can breed your own stock for grow-out in relatively small indoor tanks (even in large aquaria). Tilapia have an 8 month grow out, so if you breed in the winter you can have small fish ready for your tank when it starts to warm up in the spring.
Much of the tilapia available in supermarkets is raised on foreign fish farms, often in China. I find it very hard to trust these products. By growing your own, you eliminate the risks and achieve control over your food. Tilapia are pretty easy to raise, and can be an important supplement to your self-sufficiency program. Aquaculture units need not be elaborate, and with a bit of planning a very functional system can be cobbled together from Walmart and Tractor Supply parts on a pretty tight budget.