Commercial tilapia farming can be made much more profitable if it is hitched up to an aquaponic vegetable farm as the biofilter for the fish waste water.
This not only allows most of the water to be recirculated clean back to the fish, but also allows economies of scale to kick in. It is much less expensive to do commercial tilapia farming and hydroponic vegetable farming together as part of the same aquaponic system, than it is to operate a separate commercial tilapa farm and separate hydroponics operation.
For a start, there is no expensive mechanical filtration to do for the fish waste water. For instance, the famous University of the Virgin Islands aquaponics system, which not only farms tilapia commercially but also and at the same time is a very productive hydroponic lettuce and vegetable farm, uses just one pump and two air blowers to run an eighth of an acre of aquaponic system. This aquaponic system produces five metric tons of tilapia a year and bumper crops of lettuce, basil and other vegetables year-round in the hydroponic soilless part of the aquaponic system.
The clarifier and degassing parts of the UVI system are integrated parts of the pipe and tank work and run off the pumped water flow using baffles and orchard netting, with few moving parts to maintain. The electricity bill monthly quoted to me while I was training on this system in 2010 was around 400 US dollars a month, but this could be reduced long term by using an alternative energy source such as a bank of solar panels, a wind generator, CSP (concentrating solar power), etc. It would be interesting to get engineering data on this in the context of fuelling commercial tilapia farming aquaponics systems.
By growing feed insect larvae such as soldier fly larvae on the offcuts from the continuous vegetable harvests (weekly) bought in fish feed costs can be reduced or eliminated. It has also been possible to successfully grow duckweed, which has a higher protein content than the soybeans used in many versions of fish feed, plentifully in settling tanks and sumps of aquaponic systems, to further supplement the fish diet.
Becoming independent from outside feed sources, and feed based on fishmeal from ocean fish, would allow your tilapia to be really sustainably farmed, with the potential to further add value to it as a ‘sustainably farmed’ or using supermales, ‘organically farmed’ product in the market. However, so far as I know, no scientific feeding rates have been established for such foods as soldier fly larvae or duckweed. It would be interesting to know the established tilapia growth rates per amount of these feeds administered, and what to reasonably expect from feeding home-grown diets to the fish.
The reasons why aquaponics systems based on tilapia fish rearing can be more profitable than commercial tilapia farming on its own extend further than just being able to grow your own feed, however.
Commercial tilapia farming produces masses of fish waste water which usually ends up being disposed of into the local water table. This is really a shame, since this fish waste water turns out to be a really miracle grow fertilizer for all kinds of vegetable and soft fruiting crops such as culinary herbs, lettuce, melons, tomatoes, cucumbers, okra, and so on.
As the water is run through these crops which are grown on floating polystyrene rafts above the water flow (see illustration above), the dissolved nutrients from the mineralized tilapia fish waste water are taken up and used for crop biomass production. The result is that the aquaponic fish water returns cleaned of toxins back to the tilapia fish tanks via a sump and the single pump.
Here I must stress that this is not at all the same as commercial hydroponics on its own. Commercial hydroponics uses INORGANIC nutrient fluids dissolved in water. These inorganic chemical fertilizers, which are very expensive, are derived from the oil and gas industry, and in some cases from guano reserves on various bird habitat islands, hardly ecologically sustainable. Also the equipment used is not very similar in detail to that necessary for hydroponic farming. The piping has to be over 3 inches in diameter, for instance, and extra baffles and non-mechanical filtration devices have to be in place to stop fish mulm from clogging up the aquaponic fish water flow. A clogged up commercial aquaponics system is not profitable. It is a dead in half an hour commercial aquaponic system.
Oxygenation, as well, follows different parameters from hydroponics on its own, and has to be carefully monitored both for the tilapia fish and the plants. Ph measurements and levels are also different in aquaponics systems and have to be carefully maintained and watched. With aquaponics systems, the devil is in the details, and it will never be as fully automated in nature as a hydroponics operation on its own because of this. Fish, especially tilapia fish, bear watching frequently. If you want your commercial tilapia farm in this aquaponics system mode to be profitable, they all have to come to harvest to date and on time at the same size and the same top quality.
Using fish waste water from a profitable commercial tilapia farming operation, that is part and parcel of the integrated broad-bore pipe and floating raft hydroponic COMPONENT of recirculating water aquaponics systems, is considerably cheaper than buying in artificial fertilizer sourced from the oil and gas industry with its soaring artificial fertilizer prices. This in its turn contributes to your ability to run a more profitable business than just operating commercial tilapia farming on its own.
By feeding the fish mostly out of the by products of the vegetable harvests, a perfect circle of efficiency is created. No longer do you have to buy in large amounts of tilapia fish feed and artificial plant fertilizer. Aquaponics systems are mostly self-sustaining, and almost completely so if you are using alternative energy solutions to power the pumps, air blowers, aquaponic fish water heaters if necessary, and so on. So production costs can be kept to an absolute minimum. This is what has to happen on any profitable farm.
If you add in the low staffing ratios necessary when your farm needs no weeding, hoeing, ploughing or irrigation, all you have to do is compose the mathematics appropriate to your location and circumstances to see the accounting and economics advantages of converting your commercial tilapia farming operation into a fully-recirculating aquaponics system, or set of aquaponics systems.
However, tilapia fish can be had very cheaply as an import from China, for instance. Once of the advantages of growing tilapia fish in an aquaponics system is that a very high quality product can be achieved. This is because the water quality in an aquaponics system, where all of the nitrates are taken up by the biomass of the plants, and the solids are constantly removed daily to outside holding tanks, makes for extremely healthy tilapia fish despite the intensity of fish stocking. This contrasts with the usually mediocre quality of commercially farmed tilapia from China, where tilapia fish disease is endemic in the commercial tilapia farms, one assumes due to poor aquaponic fish water filtration processes. So using aquaponics as the profitable biofilter for your commercial tilapia farming can also make your commercial tilapia product more competitive as a quality sustainably farmed fish.
If you have more specific questions about aquaponics, the world’s leading expert on commercial aquaponics, my old teacher at the University of the Virgin Islands, Dr James Rakocy, has brought out a Q and A answering book that is really clear and helpful: