Tilapia farming has become one of the rapidly growing sectors in the Indonesian fisheries industry. With increasing market demand, both domestically and for export, tilapia farming offers highly promising economic prospects. In this farming process, one of the crucial stages is fry rearing or commonly known as "nursery." The nursery plays a central role in determining the overall success of tilapia farming, as it is at this stage that the fish fry are raised until they reach a certain size ready to be transferred to grow-out ponds or sold to other farmers.
The process of rearing tilapia fry involves several important stages, starting from larval rearing to producing fish fry that are uniform in size, both in terms of length and weight. This size uniformity is a very important factor in fish farming as it influences even growth, efficient feed utilization, and minimizes cannibalism among the fry. Through well-planned and executed rearing stages, farmers can ensure optimal fry quality before proceeding to further grow-out stages.
Furthermore, the nursery activity aims to provide tilapia fry in sufficient quantities, both in terms of quality and production continuity. The availability of good and measured fry is crucial to support the needs of tilapia farming, especially on a large scale. Based on research by Afriani (2016), tilapia nursery activities are generally carried out in two to three stages, with each stage having different stocking densities. This stocking density significantly determines the growth of the fry and their survival rate, where each stage has a density standard adjusted to the size and needs of the fry.
Objectives and benefits of tilapia nursery
The main objective of the nursery activity in tilapia farming is to produce fish fry with uniform size, both in terms of length and weight. This uniformity is vital because it provides each fry with an equal opportunity to access feed. When all fry have a relatively similar size, competition for food will be reduced, allowing for even and consistent fry growth. Therefore, the primary goal of the nursery activity is to ensure optimal growth for all fish fry in a batch and prevent cannibalism, which often occurs when there are significant size differences.
In addition, nursery activities also play an important role in maintaining the availability of tilapia fry in sufficient quantities. The number of fry available must match the market demand and the grow-out ponds to be stocked. Fry quality is also a major focus, as high-quality fry have a better survival rate and can grow faster.
The stocking density of fry at each stage significantly influences the success of the nursery. In the initial stage, the first stage, the recommended stocking density is 75-100 fry per square meter. In the second stage, the stocking density is reduced to about 50 fry per square meter to provide more space for the fry that have started to grow larger. In the third stage, the stocking density is further reduced to 25-30 fry per square meter, so that the fry have enough space to move and grow bigger. After passing the second stage, the fry are usually ready to be transferred to grow-out ponds to continue their growth process until they reach consumption size.
Tilapia larvae rearing
The initial stage in tilapia nursery activities begins with larvae rearing. During larvae rearing, tilapia fry are fed fine pellets with high protein content. Feed quality significantly determines fish growth, and good feed should contain complete protein, fat, carbohydrates, vitamins, and minerals. Feeding is done according to the fish's body weight, which is about three percent of the fish's body weight or ad libitum (as needed). The feeding frequency is three to five times a day.
In addition to artificial feed, tilapia larvae can also be given natural feed according to their mouth gape. This natural feed is important to meet the nutritional needs of tilapia fish during their growth period. As the larvae grow, the protein dosage in the feed should be reduced to match the nutritional requirements of the larger fish. The growth and development of the fry can be observed from the increase in their body weight and length.
The first stage of the nursery
The first stage in tilapia nursery activities is a critical phase that begins with the rearing of fish fry measuring 1-3 cm. At this stage, the fry are reared for a period of 3-4 weeks with the aim of reaching a size of 3-5 cm per fish. The rearing process involves feeding fine pellets containing 10-15 percent protein of the fish biomass weight. Feeding is carried out routinely three times a day in the morning, afternoon, and evening to support optimal fry growth.
During this phase, it's important to monitor and ensure that each fry receives sufficient and quality feed. At the end of the rearing period, fry harvesting is done using a scoop net. After harvesting, the fry that have reached the size of 3-5 cm are selected through a grading or sorting process based on size. This process aims to ensure uniformity in the size of the fry that will proceed to the next stage in the nursery.
The fry that have reached the desired size will be transferred to grow-out ponds or to the second stage of the nursery to continue their growth process. Meanwhile, fry that are still small in size remain in the pond to reach the appropriate size. In this way, tilapia fry can grow evenly and be ready for the next stage in the cultivation process.
Tilapia fry measuring 3-5 cm: Agro Ceria Kota Metro
The second stage of the nursery
In the second stage of the nursery activity, tilapia fry that have gone through the first stage and are 3-5 cm in size are reared again to reach a size of 5-8 cm. Rearing lasts for three to four weeks, where the fry are fed three times a day using pellets with a lower protein content, around 7.5-10 percent of the biomass weight. Feeding is still done regularly in the morning, afternoon, and evening to ensure optimal fry growth.
During this second stage, the mortality rate of tilapia fry usually reaches 20 percent, so more intensive care is required. Farmers must pay attention to water quality, feed management, and pond environmental conditions to minimize mortality rates. These factors significantly influence the success of rearing in the second stage. Additionally, closer monitoring is also needed to prevent the occurrence of diseases that can spread among the fry.
Once the tilapia fry reach a size of 5-8 cm, harvesting and grading are carried out again to ensure size uniformity before the fry are transferred to the next stage. This grading is important so that the resulting fry have uniform quality and are ready to be transferred to the third stage grow-out ponds or directly sold to other farmers. At this point, the fry that have reached the ideal size have a high market value, so good rearing practices significantly influence the success of the tilapia farming business.
Tilapia fry measuring 5-8 cm: BRPI Sukamandi
The third stage of the nursery
The third stage in tilapia nursery activities is a continuation of the second stage, where fry measuring 5-8 cm are reared until they reach a size of 10-12 cm. Rearing at this stage usually lasts for 4-6 weeks, with feed provided three times a day using pellets that have an even lower protein content, around 5 percent of the biomass weight. At this stage, the focus of rearing is more on accelerating fry growth to a larger size, although the feed provided is no longer as dense as in the previous stages.
However, this third stage tends to be rarely carried out by tilapia farmers. One of the main reasons is the high market demand for fry sized 3-8 cm, so many farmers prefer to sell the fry at that size. The 3-8 cm fry size is considered ideal for market needs because many buyers prioritize fry that are ready to be transferred to grow-out ponds. This condition makes farmers focus more on the first and second stages to meet the high market demand.
Nevertheless, for farmers who choose to produce their own fry, the third stage remains an essential part of the cultivation process. At this stage, the fry that have been reared to reach a size of 10-12 cm are considered more ready to be grown to consumption size. Farmers who proceed to this stage usually aim to maintain the quality and continuity of tilapia fry production that can be raised to reach commercial or consumption size.
