Tilapia is one type of freshwater fish consumption with an elongated body shape and flat to the side with a blackish white color. Tilapia comes from the Nile River and the lakes around it to spread to countries on five continents with tropical and subtropical climates. This fish is quite popular with the people of Indonesia. The reason is because of the thick texture of the meat and its delicious taste, making it suitable for the Indonesian tongue. In addition, Tilapia has been widely cultivated so that almost every area has a cultivation pond for this type of fish.

Fish farming activities that are commonly carried out by the community are fish enlargement (fattening) activities. Broadly speaking, fish rearing is a stage of aquaculture activities that aim to produce fish sizes that can be consumed and have economic value. The size of tilapia for the domestic market ranges from 300-500 grams/head. It takes about 4-6 months to keep tilapia from 10-20 grams to 300-500 grams. To start  tilapia enlargement, of course, we must know in advance the stages and techniques of good tilapia enlargement. The stages are as follows:

1. Preparation of the enlargement pond

Ponds used for tilapia enlargemet can use various types of ponds, such as ground ponds, concrete ponds, tarpaulin ponds, floating nets to brackish water ponds. Of the many types of ponds, the ground pond is the most widely used because the method is quite easy to make and the construction cost is cheap. Another advantage of the ground pond is that it can be used as a place to grow various plants and animals that are useful as natural food for fish. So it can reduce the cost of buying artificial feed or pellets. Preparation of the ground pond begins with drying the ground, reversing the ground, liming the ground, and filling water which is carried out for approximately two weeks. The steps are as follows:

• Drying the bottom of the pond. The pond is dried by drying. Drying usually lasts for 3-7 days, depending on weather conditions. As a rule, drying is sufficient if the surface of the soil looks cracked, but not stony. When stepped on it still leaves footprints as deep as 1-2 cm.
• Next, the ground surface is plowed or hoeed to a depth of approximately 10 cm. Garbage, gravel and other debris are cleaned from the bottom of the pond. Also clean the black mud that smells bad, usually comes from the rest of the feed that is not used up.
• Ponds that have been used usually have a high acidity level (low pH), less than six. Even though the optimal pH conditions for tilapia cultivation are in the range of 7-8. To neutralize it, do liming with dolomite or agricultural lime. The dose of liming is adjusted to the acidity of the ground. For soil pH six as much as 500 kg/ha, for ground pH 5-6 as much as 500-1500 kg/ha, for ground pH 4-5 as much as 1-3 tons/ha. The lime is stirred evenly. Try to let the lime get into the ground surface as deep as 10 cm. Then let stand for 2-3 days.
• After that do fertilization. Use organic fertilizer as basic fertilizer. The type can be compost or manure. Giving organic fertilizer is useful to restore ground fertility. The dose is 1-2 tons per hectare. Fertilizer is spread evenly at the bottom of the pond. Leave it for 1-2 weeks. After that, if deemed necessary, chemical fertilizers can be added in the form of urea 50-70 kg/ha and TSP 25-30 kg/ha, let stand 1-2 days. The purpose of fertilization is to provide nutrients for animals and microscopic plants in the pond environment. So that these animals or plants can be used as natural fish food.
• Then, the pond is flooded with water. Irrigation is carried out in stages. First, drain the water into the pond as deep as 10-20 cm. Then, let stand for 3-5 days. Allow sunlight to penetrate the bottom of the pond perfectly, to give algae or other aquatic organisms a chance to grow. After that, fill the pond until the water level reaches 60-80 cm.

2. Seed selection

The determining factor for the success rate of tilapia rearing cultivation is the selection of the right seeds. For maximum results, you should use male fish seeds that have received official certification. Tilapia cultivation should be done in monosex (same sex). This is considered more productive than a mixture in one pond. Because tilapia has the nature of easy spawning (mating). So that if the cultivation is carried out in a mixed manner, the fish's energy will be used up for spawning and the growth of fish weight will be slightly hampered.

The characteristics of good and superior tilapia seeds are healthy, agile movement, not disabled, bright body color, not carrying disease/parasites and responsive to feed. The easiest way to see healthy fry is to look at their swimming direction. Healthy fish will swim against the current, so they will always be in the air intake. On the other hand, fish that are not healthy/weak will be in the exhaust section or stay at the bottom of the tub.

3. Stocking seeds

Tilapia seeds that will be stocked in the enlargement pond are acclimatized first to adjust the temperature in the new environment. Acclimatization aims to adjust the new environmental conditions to the previous environment, in other words the water temperature in the plastic bag is equalized with the water temperature in the enlargement pond.

The simple way is to put a container containing tilapia seeds into the pond water and let it sit for a few minutes. Then tilt or open the container. Then, let the fish fry out by itself. Equipment and materials that can be used include plastic, water, and oxygen.

4. Tilapia maintenance

• Fish feeding

Tilapia were fed with an amount of 3% of the fish's body weight with a frequency of two times, in the morning and evening. Feeding two times a day with a Feeding Rate (FR) of 3% of fish weight can increase the body weight of tilapia optimally. In accordance with the statement of Popma and Lovshin (1994), fish body weight increases optimally when fed 2.5-4% of fish body weight. The type of feed given is in the form of pellets of 3 mm size floating type for  tilapia enlargement.

Feeding of course must be calculated based on the weight of the fish in a certain time cycle. This is known as the Feed conversion ratio (FCR). FCR (Food Conversion Ratio) is the ratio between the weight of fish feed that has been given in a certain period cycle, with the total weight (biomass) produced. The smaller the FCR value, the better indication of high quality feed (USAID, 2011).

• Fish growth review

Growth is an increase in size, length, and weight at one time (Riani, 2012). To determine the growth of fish, it is necessary to do fish sampling once a week. Sampling is also useful for determining the amount of feed to be given to fish according to their growth. The average growth rate of male tilapia is 2.1 grams per day, while the average growth rate of female tilapia is 1.8 grams/day (Ghufran, 2009). Equipment and materials that can be used include 50 tilapia, ruler, and digital scales.

• Water quality management

In order to maximize the growth of tilapia cultivation, monitor the quality of the pond water. The parameters that determine water quality are the oxygen content and pH of the water. In addition, we can also monitor the levels of CO₂, NH₃ and H₂S if possible.

If the oxygen content in the pond decreases, increase the water circulation by increasing the flow of water discharge. If the pond already contains a lot of NH₃ and H₂S which is marked by a bad smell, immediately replace the water. You do this by removing dirty water as much as 30 - 50% of the total pond water. Then add new water.

Water quality can be measured daily or at least two times a week with parameters of dissolved oxygen, temperature, brightness, and pH. Equipment that can be used include DO meter, pH meter, and secchi disk.

• Pest and disease control

Tilapia is known as one of the fish that is quite tolerant of extreme water conditions. Under normal circumstances, tilapia disease is not much of a concern. However, if tilapia cultivation has been carried out intensively and massively, the risk of disease attacks must be watched out for. The spread of fish diseases is very fast, especially for the types of infectious diseases that are contagious. The medium of transmission is usually through water. So it can reach one or more pond areas. For further explanation, please read the following article click here

5. Fish Harvesting

The time required for tilapia cultivation from seeding to harvesting refers to market needs. The size of tilapia for the domestic market ranges from 300-500 grams per head. It takes about 4-6 months to keep tilapia from 10-20 grams to 300-500 grams.

Tilapia is predicted to be harvested after four months of rearing or after reaching consumption size. Fish are harvested by shifting using nets and pellets to bait fish. The harvesting techniques for cultivated tilapia include total and partial harvesting. The total harvesting technique is done by drying the pond to a water level of about 10 cm from the bottom of the pond. harvesting plots are made with an area of 1 m in front of the exit door. While the harvesting technique is partly done by not drying the pond water, but through selecting fish based on certain sizes needed by consumers.

The advantages that we get from cultivating tilapia include the following:

• No need to spend big capital. We only need to cultivate 1,000 tilapia fish, we only have 5–10 million in capital, where that capital will get a pretty big profit too.
• Tilapia is classified as having a relatively fast growth period, so we only need 3-5 months for harvesting.
• Tilapia care is easy. Tilapia is a type of fish that is easy to find seeds or seeds. Not only that, tilapia is also a fish that rarely gets sick.
• The selling price of tilapia in the market is relatively stable. The price of tilapia in the market rarely declines, this is certainly an advantage for those of us who are already cultivating tilapia or just want to start.
• Tilapia has many fans. Not only purchased for small-scale daily needs at home, tilapia is also used for food in restaurants, medicine and others.

References

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