As I have stated in a previous blog post, the 4 key factors for rearing tilapia are water, air, food and good stock. If one of these isn't right, you have a lesser quality fish or perhaps dead fish. Let's look briefly at each of these items.
Firstly is the species and the quality of the fish. We raised Nile tilapia which are the most popular for a few different reasons. These grow fast, are hardy, and start breeding at 4-5 months. You should source your fish from reputable tilapia suppliers who have given their fry hormones to alter the sex to males. This will be done before you receive them. The suppliers can't guarantee 100% males but the ratio is much higher with the hormone. Male tilapia grow faster and are therefore the preferred sex to have as stock.
Water and the quality of the water.
Other considerations regarding water is the depth, temperature and the Ph balance of it.
Regarding depth tilapia can live in virtually no water. I have seen them wallowing in a muddy pool only a few inches deep. This of course is not a good condition for your fish to be in. Aim to have a depth of at least a meter and a half. Depending on the number of fish you plan to raise there should be some way of moving water to reduce the risk of algae. The greater the number of fish the more air you will need and the more likely you are to have algae as a result of the fish poop which algae loves. Discussing algae will be covered in a later post. There are good and bad reasons to have it.
Temperature is also something you need to keep an eye on. Depending where you live you may need to heat the water. Tilapia are pretty tolerant fish and can take quite high temperatures but of course for maximum growing you want optimum conditions. (or at least as close as you can get).
Air for fish farming
Air might not seem like an important ingredient in raising fish, after all they aren't air breathing. When you see your fish on the surface gasping for air, you will realize they do. We thought we had enough air in the water because we have a strong wind. Where we live in northeastern Brazil is known for its kite surfing because of the wind for many months. During the day the wind would blow and the fish were fine. At night the wind would reduce and this put undue stress on the fish.
This wasn't only because of the reduction in wind however. During the day, algae produces oxygen but during the night it consumes it.
To ensure our fish would not only survive but thrive until harvest time, we bought two aerators.
The type we bought floated on the surface and sucked water from beneath throwing it like a fountain into the air. We held these in place with line strung from one side to the other.
Their are other systems in place for pond, lake, tank or even river aeration. This is a decision which shouldn't be taken lightly as the welfare of your fish depend on it.
For maximum growth in the shortest amount of time, purchase commercially prepared food. It will have all the ingredients necessary to encourage growth for the age of your fish. The fish pellets we used contained soya products which are from genetically modified strains. Brazil has crops of soya and maize which are GM. If you are concerned about this it may be possible to source GM free fish foods. Although we bought the type recommended, from a local factory it is possible to buy a 'carnivore' type. This apparently has a higher protein content which is what makes the fish grow. One of the farmers I have mentioned earlier bought this type. The factory we used was called Guabi and I believe they sell throughout South America.
After your intital purchase of fish and equipment, the food will be your biggest cost. If you are harvesting only once a year, you need to ensure you have enough capital to buy the fish food until they are ready to be harvested. Depending on the number of fish you plan to raise and how big you want to harvest them at, you are likely looking at several thousands of dollars (or whatever currency you work in.).
We found that people who started this business didn't take into account the high cost of food when they bought their fish. It is also the reason some people have to sell the fish before they are 'market ready' , they have simply run out of money and can no long afford to feed them.