Water, Air, Food and Fish. The 4 Key Ingredients to Fish Farming

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.

Tilapia

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.

Tilapia although a freshwater or sweet water fish can tolerate some brackish water. I know of one farm here who's water turns brackish as the sea comes up the river at high tide. This is useful because it will help clear the fish shit out to sea. The external color of tilapia will darken with the presence of salt in 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.

Tilapia Food

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.

How to Feed Tilapia

If your tilapia are free swimming in a lake as ours were I would like to tell you how we fed them. In future posts I will tell you about the other ways of rearing tilapia such as in tanks, cages. Here though this is specifically about feeding in a closed lake.

Begin by weighing out the correct amount of tilapia food. Depending on the age, as determined from the feeding chart. This can be done with a simple kitchen scale. Correct food amounts are important for two reasons.

1. you don't want to underfeed them. This would of course would slow down the growth of your fish.

2. If you overfeed them, the food and money will be wasted. This not only causes problems to your budget but also your lake.

We found simply standing at the edge and throwing it in worked best for us. We found using an old ice cream tub worked well. We tended to spread the food in a wide arc to ensure the food covered a wide area. You will notice the fish, will be waiting for you to arrive. They know their feeding times.

As they come to the surface it is encouraging to see them eagerly eating. It is also a good opportunity to see the speed at which they are growing.

There are companies which make devices which catapult the feed into the lake. We didn't find this to be necessary however if you have a large lake or more fish, this could be an option for you.

One thing to keep in mind is you may get other animals eating your fish food when you feed your fish. We had geese at the time and they stormed in to help themselves to the floating fish food. As much as I liked having geese, this behavior wasn't acceptable and in the end we sold them.

When we moved to rearing our fish in cages, we found moor hens would help themselves to the food. This proved more difficult to control. One of the topics I will be discussing in future posts is the wildlife which you may see and the pros and cons of them.

Storing Tilapia Food

Correct storage of tilapia feed is critical. You don't want to run out but you also don't want to store too much. There are a few reasons for this. Like anything the commercial fish foods have a expiry date. Obviously opt for sacks with the longest date possible. Also, as mentioned previously opt for specially prepared food which is suitable for the age of your fish. This will result in the best growth rate possible.

The tilapia food we bought came in sacks weighing 25 kilos. Now neither myself nor my husband are spring chickens but between us we managed to moved them. We just carried them but if you are going to move them any great distance, consider using a wheelbarrow. Here in Brazil, it is not uncommon to see men carrying this weight on top of their heads! I have even seen someone deliver a refrigerator by carrying it on their head. Sorry, I am going off topic, a bit.

The food should be stored somewhere dry and well vented. It also should be raised off the floor. Using pallets is ideal for this. It is also a good idea to put down poison for rats and possibly some cockroach bait boxes. You will be spending a lot of money on fish food, so protect it from animal or pest infestation.

It is a good idea to keep the area swept clean so you can see any droppings left by pests.

As with anything which has a shelf life, always rotate your stock so you are using the oldest first.

Growth Rate in Tilapia

After the arrival of the fish we were committed and were now fish farmers. Although feeding isn't recommended for a couple of days after arrival we went and bought food to ensure we were ready to start feeding when the time was right. 

As I have said, the factory is only a short drive and we have a VW Kombi so we could collect it. This made it easier as we had no delivery charge and we knew we could always get it when we needed it. It also meant I wouldn't be sitting on too much at one time.

The food for tilapia is in pellets. These vary in size depending on the age of the fish. They also vary in nutrition as well. That is one of the reasons I don't suggest buying just any fish food. The requirements of the fish vary at different stages of their life. Towards the end of their growing they are given ingredients to fatten them up.

Tilapia are a fast growing fish and with the correct nutrition, can increase their weight by 3 grams a day. 

The chart on the previous post shows the correct amount for each stage of the growing period.

Feeding Chart for tilapia

Size of feed pellets	Weight of fish (grams)	Age of tilapia (weeks)	Number of feeds per day	Daily amount per 1000 fish
Powder	0.5-2	1	12	225g
Powder	2-3.5	2	10	440g
Powder	3.5-5	3	10	680g
1.7mm	5-7	4	9	600g
1.7mm	7-12	5	8	760g
1.7mm	12-20	6	7	1.1kgs
2-4 mm	20-30	7	5	1.5kgs
2-4 mm	30-50	8	5	2.0kgs
2-4 mm	50-75	9	5	3.1kgs
2-4 mm	75-100	10	5	4.4kgs
4-6mm	100-115	11	4	4.8kgs
4-6mm	115-140	12	4	5.7kgs
4-6mm	140-170	13	4	6.2kgs
4-6mm	170-200	14	4	7.4 kgs
6-8mm	200-240	15	3	8.8 kgs
6-8mm	240-280	16	3	9.1kgs
6-8mm	280-325	17	3	10.6kgs
6-8mm	325-370	18	3	12.2kgs
6-8mm	370-420	19	3	11.9kgs
6-8mm	420-475	20	3	13.4kgs
6-8mm	475-535	21	3	12.6kgs
6-8mm	535-595	22	3	11.3kgs
6-8mm	595-660	23	3	12.6kgs
6-8mm	660-725	24	3	13.9kgs
6-8mm	725-795	25	3	11.4kgs
6-8mm	795-870	26	3	12.5kgs
6-8mm	870-945	27	3	13.6kgs
6-8mm	945-1025	28	3	14.8kgs
6-8mm	1025-1110	29	3	16kgs
6-8mm	1110-1200	30	3	11.6kgs

Getting Advice on Quantity of Tilapia

When we started mentioning to people we knew that we wanted to start raising fish, everyone was an expert. They of course had never raise tilapia other than perhaps for their own consumption. Their idea was to put the fish in there and basically throw in whatever you wanted to feed them. They would throw in bread, rice, whatever was left over. We might not have raised fish before but we knew this advice was nonsense.

Luckily for us, the company which manufactures fish food is about 15 minutes up the road from where we live. They have a representative who came out to see our set up and discuss our options. We also were taken to another tilapia farm near-by whose workers were very helpful. When the man arrived we were told we could put 2,500 fish in our lake in front of our house. That was without additional aeration. Our lake is approx 50m X 50m and at the time was 7' deep.


 We got the telephone number of the company which sells fish and placed our order. We bought 2,500 tilapia weighing 30g each. These arrived in aerated tanks on the back of a truck. The truck changed the water with water from our outside hose. After that the tilapia were unceremoniously scooped out into crates and tipped into the lake. Our lake already had fish in it. Although we had netted it, it is almost impossible to remove all the fish in a lake. Some had been bought and others arrived on birds feet as eggs, it was a always a surprise when we fished it, what we pulled out. We did have two types of predator fish in the lake. The peacock bass and a fish called a triara. I will be talking about the need for predators in future blog posts.

 As our new fish were being tipped into the lake, the bass and triara were gobbling up as many as they could. It was like a feeding frenzy and was hard to watch our money being gobbled up right in front of our eyes. With the tilapia, as I imagine is the case with vast numbers of livestock, a 10% rate of mortality is expected. This could be weaker stock which couldn't take the moving or possibly shock of the new environment. Over the next few days, we had what seem to be a lot floating to the surface.