Aquaponics and Tilapia Farming, the Perfect Combination

When we first began our tilapia farm, we were told about how to maximize our revenue by using three levels. The young man who told us was studying fish farming at the university in Fortaleza. What was suggested for non-commercial tilapia farmers was to have ducks, tilapia and shrimp. The theory behind this is all the space was being used.

The ducks obviously on the surface, eating the vegetation in and around the lake and then defecating in the water which increased the algae for the tilapia.

The tilapia then poop and the shrimp eat that. All of that natural fertilzer keeps the vegetation growing and so the cycle continues.

This, in my opinion is a good system as you can get paid 3 times for that body of water.

However, there was one problem we found with this system. It was the ducks.

Now don't get me wrong I love ducks. I love watching them swim, I love the eggs, I love eating duck but... they would eat our tilapia food. At first it was amusing to watch them swim over waiting for us to feed the tilapia.

By the end though, it was evident that we had to do something about the problem, so we sold the ducks.

That left us with the surface of the water not earning us money. That is until we thought about aquaponics. The revelation came to us with how well our water hyacinths were growing on our lake we had fish in. Our other lakes (without fish) also had some hyacinths but the plants weren't growing very well. That was when the light bulb went on.

It all that goodness in the water which was feeding the plants.

Not only would we have enough for ourselves but we would have enough to sell.

My husband and I tend to be a little cautious and we thought for awhile whether it was doable. We didn't want anything which was too labor intensive as we already had enough work with the farm and the fish.

It wasn't until I returned home from the supermarket with a scrawny looking head of lettuce, which I had paid R$2.00 (Brazilian reals). When he saw this and knew what we could produce with aquaponics, we began straight away.

Once we got into our routine, and asked at the local shops if they wanted to buy, all of them did. They knew their customers would love our lettuces and other plants as they were much deeper green and healthier looking than what they were currently selling.

My only regret with the aquaponics system is that we didn't start sooner. Not only would we have been making more money sooner but it would have taken that worry about keeping all your eggs in one basket.

I mean tilapia farming is almost a guaranteed return on investment but there are things which can go wrong. With aquaponics, that gives us a buffer of cash just in case the unforeseen should happen.

Tilapia farming and climate change

Not a day passes that you don't hear something  about climate change. Often this has turned more into a finger pointing exercise of which countries pollute unnecessarily whilst other countries become a victim to the ravages of the weather caused by these changes.

However behind the scenes there are countries who are preparing for these changes. For example, universities in the countries of Norway, Finland and the Netherlands have come together to discuss what can be done to prepare for the changes to fish farming as a result of climate change.

One of the topics they touched on was selective breeding. This would be cross breeding with weather hardy types to produce a fish which is still acceptable to the consumer but can stand temperature fluctuations.

Although their talks were centered around farmed fish such as salmon, this is also a necessary topic for tilapia. Currently fish are, in the main, raised in areas which are warm due to the fact that to heat a large volume of water is costly.

Here in Brazil we have a constant temperature year round which makes it ideal for the rearing of almost any fish. The ideal temperature is 86°F (30° C). As the temperature decreases the fish are using the food to keep their body warm and not to increase the weight. If the temperature is too hot, the fish become stressed and will stop eating also not ideal. .

Climate change  could see areas which were once too cold to profitably farm tilapia opening up to potential boom times. Under the right conditions, you can harvest in 5 months. This is a quick turn around and can be very profitable. Even if winters are still cool, an early warm spring could see the introduction of tilapia in many areas which were once considered unsuitable for this tropical fish.  

Tilapia cages. What makes a good one?

Although you may have heard that the tilapia can be successfully reared in a cage, you may not have realized just what is needed. There are some I have seen on sites such as Ebay. These are a thin netting material with floats. Often these will be for very young fish as the material is not robust enough for adult fish. A cage in many ways is preferred to rearing in a tank because the fish waste drops through the cage to the bottom of your lake or river.

Here on our farm we have used a few different types, some are better than others for various reasons. Here are a few things to consider.

The frame. What material is the frame made of? This could be aluminum, wood or plastic pipe. Each has its advantages and disadvantages.

material	Pros	Cons
Plastic pipe	Lightweight, inexpensive and readily available, easy to fix	May deteriorate in the sun
Aluminum	Lightweight, doesn't rust	Needs to be a good quality otherwise will bend with weight of fish
Wood	We used Hardwood which lasts	Can be heavy to lift, out of the water could be prone to insects.

Besides the frame which will hold the netting or the structure of the cage. For this we have used two types. One was a heavy duty plastic, the other was plastic coated metal. Similar to a chain link fence.

Over time both of these needed repairing as areas would become holed and allow fish to escape.

Every time the cages came out of the water for the fish to be sold, they get cleaned and thoroughly checked for potential problems. The plastic ones we repair with strong cord, and the metal ones we use coated wire to patch up areas.

You also need a way of making the cages float as you do not want the cages sitting on the bottom of your body of water. We use plastic cans which in their previous lives were used for cleaning products. These were perfect but after two years in the Brazilian sun, needed replacing as they became brittle and would crack and take on water.

This is why, during feeding time, it is always a good idea to do a quick visual scan of the cages to preempt any potential problems. Keep extra buoyancy aids in a covered area. It would be a shame to see all the fish in your cage escape due to a listing cage.

We had a local welder construct small cages to hold the containers in place. These simply hooked over near a corner. On our 2m x2m cages we use 4 floats. On our 2m x 3m we use 6 floats.

As well as the frame, the cage material, and the floats you will also need to put fabric mesh around the top edge of the cage. Ours was about 18” wide. At first this doesn't seem necessary but when you feed the fish in the cage, this mesh will keep the food from floating out of the cage and being wasted. This should be tied onto the cage to keep it from floating up, which trust me, is a nightmare.

The last item you will need is plastic mesh for the top of your cage. This serves a couple different purposes. One is to keep the fish in the cage. Although you may think that tilapia don't jump, they will. With a cage which is just floating above the height of the water, they will be out in a shot. The second reason is to keep out birds. We have had herons, egrets and moorhens all sitting on our cages. The herons and egrets are trying for the fish and the moorhen is eating the fish food.

Triploid Tilapia

Triploid fish are those which are sterile with three sets of chromosomes and as such will never be able to reproduce. So why would we want these sterile fish and how do we get them?

The use of hormones and antibiotics in food has skyrocketed. Not only does this have a cumulative effect on humans as we eat the meat  but also on marine life as it is eliminated and flushed out of our system into the sewers and eventually ending up in the world's oceans. We of course eat the seafood and have another dose of hormones and unwanted chemical cocktails by doing so.

So what's the answer? It could be triploid fish as this is already being seen in trout and other fish as a viable method of population control in by the US. I feel our role as  farmers is not to add to this problem but to try and eliminate  hormones from the cycle of tilapia farming if possible.

Although the treatment of hormones with 17 alpha-methyltestosterone is commonly used here in Brazil there are alternatives.  The use of cold and/or heat shock and  pressure treatment on fertilized eggs can leave the fish sterile.  This is achieved by applying  the  pressure, heat and then cold to the eggs shortly after they have been fertilized. The amount of pressure, and time held during the  heating  and chilling period are crucial to get the triploid tilapia. Too much of any of those processes and the eggs will die , not enough and it is likely to be ineffectual.

Beside saving hormones from entering the food chain, producing triploid fish is safer for the environment, as tilapia if they escape into rivers and lakes, can be an invasive species. Their rapid breeding can soon get out of hand and cause problems in many bodies of water.

It is down to tilapia farmers  to seek out alternatives and find   breeders who  are not  using hormones as a method of sex reversal.