Fish is one of the foods that are often consumed by humans because it has a lot of nutritional content that is good for humans. According to Astawan (2004), fish contains essential amino acids that are quite complete and indispensable to humans. However, fish is one of the perishable food so it is very easy to experience the deterioration process and get damaged due to various factors.
In order to prolong the shelf life of the fish, proper management is necessary after the fish has died and entered the rigor mortis phase. One of the things that can extend shelf life is the temperature of the fish’s storage environment. At low storage temperatures, such as storage in fridge, fish life is improving. This is because the growth of bacteria and biochemical activities such as enzymes are inhibited and the quality of the fish can be maintained.
Definition of fish
Fish is one of the plentiful food products and is commonly consumed by various groups of people in Indonesia. Fish is also one of the protein rich foods because the absorption of protein from fish is higher than other animal products, both beef and chicken.
Fish meat has shorter protein fibers than beef and chicken. In addition, fish is also rich in various vitamins and minerals as well as essential fatty acids such as omega-3 and omega-6 which are very beneficial for the body as well as complete amino acids needed by the body.
Normally, in 100 grams of fresh fish meat contains 18 grams of protein, while in 100 grams of dried fish there are 40 grams of protein. However, the protein content of fish also depends on the type of fish (Pangkey, 2011). Of course, there are several types of fish that can be consumed by the community. Some of them are tilapia, tilapia and goldfish.
Types of Fish
Here are the types of fish, among others:
Tilapia fish (Oreochromis mossambicus) is a type of freshwater vertebrate fish originating in African waters. This fish is a tropical fish that likes shallow water and is classified as a type of fish resistant to environmental changes. The ideal salinity for tilapia to grow is 35 ppm. The head of the tilapia fish resembles a tilapia, that is, cones and ovals in front. The eyes of tilapia fish are reddish, black and some are brown. The body shape is flat and elongated, it has small scales, there are vertical lines on the body and a red line on the tail fin. The color of tilapia fish is influenced by the fish’s environment or habitat. The ideal temperature for growing tilapia is around 20-27OC. The protein content of tilapia fish is 18.2% and 0.7% fat (Harahap, 2014).
Goldfish (Cyprinus carpio) is a type of freshwater fish widely cultivated in Indonesia. Usually, the habitat of this fish is certain freshwater lakes, in rice fields along with rice, lakes and other public waters. Unlike tilapia and tilapia, goldfish are very sensitive to environmental changes, but carp can survive in aquatic environments with low levels of dissolved oxygen and also in situations of supersaturation. The ideal temperature for carp growth is 25-30OC with a salinity of 35-30 ppt (Rudiyanti and Ekasari, 2009). The characteristics of the goldfish are having an elongated body and slightly flattened to the sides, large fins, fork-shaped tail and rather large circular scales and the mouth is located at the middle end. The protein content in carp is 18.3% and the fat is 5.8%.
Oreochromis niloticus or commonly known as tilapia is one of the freshwater fishery products that are sought after by the people of Indonesia. Tilapia has a specific flavor, dense meat, easy to serve, few spines, easy to obtain and relatively affordable. The appearance of the tilapia resembles that of a tilapia, but the back of the tilapia is taller and thicker.
The vertical lines along the body are lighter than the body of the caudal and dorsal fins, the eyes are prominent and relatively large and the white edges of the eyes are also one of the characteristics of tilapia. The protein content of tilapia meat is 17.5%, fat 4.7% and water 74.8%. Another advantage of tilapia is that it is relatively easy to grow, relatively resistant to environmental changes and various diseases.
Normal growth temperature in tilapia is around 14-38OC while at temperatures below 6OC and above 42OC tilapia can die. The salinity level suitable for the growth of tilapia is 0-28 ppt, while in salinity above 29 ppt, its growth can be stopped (Ardita and others., 2015).
fish growth stage
The following are the growth stages of fish, including:
1. External Phase
- Food (quality and quantity)
- Water chemistry (turbidity, 02, C02, pH, alkalinity, NH3, H2S)
- water temperature; In seasons, the ideal temperature for growth is before and after summer. This time is called the growing season. While in the tropics the temperature is generally optimal
2. Deep Phase
- Sexual factors, when the gonads first mature, growth slows down because energy is used for nest building, spawning and guarding the offspring.
- Age, fish age between 3-5 fast growth, old fish slow growth, because energy is used for body maintenance and movement.
- Diseases, especially diseases that attack the digestive system or vital organs, so the energy is used for healing.
Calculating fish growth
Wt = Wo egt
gt = In Wt/Wo
Wt = Weight at time t
Wo = starting weight
G = growth coefficient
Lt = L∞ [1 – e-K(t-to)]
Lt = L∞ (1-e-Kt) + Lo e-Kt
Lt = Length at time t
L∞ = Maximum length
Lo = initial length
SR% = Nt/No x 100%
SR = Survival
Nt = Number of fish at time t
No = Number of fish at time 0
SGR = (WB/Bo – 1) x 100%
SGR = Growth Rate
W = Time spent
B = Final body weight (g)
Bo = initial body weight (g)
Factors that affect hatching
The factors that influence the occurrence of hatching are the presence of oxygen, temperature and light.
In some experiments it has been shown that due to lack of oxygen it can stimulate the respiratory activity of the embryo and there seems to be a relationship between the respiratory activity of the embryo and hatching. Temperature is also an important environmental factor in the incubation process.
An increase in temperature can also stimulate the secretion of hatching enzymes. Once the enzyme is excreted, carion digestion is faster at high temperatures than at low temperatures, leading to faster hatching. For other environmental factors that can affect hatching is light. In these factors, it appears that the secretion of hatching enzymes is controlled by stimulation of the “eye and/or pineal gland” photoreceptors, possibly via the central nervous system.
Several other factors affect the secretion of hatching enzymes in fish. Epinephrine and MS-222 at low concentrations were able to accelerate the secretion of hatching enzymes in background embryos, while tobocurarine, atropine and MS-222 at high concentrations were able to inhibit secretion.
Factors that affect fish damage
The high nutritional content of fish makes fish classified as a food high risk. Fish meat spoils more quickly than mammalian and poultry meat due to the amount of tendon which is so small in the body of fish that it is very easily digested by enzymes found naturally in fish that can cause autolysis.
Therefore, the spoilage process of fish becomes faster than other types of meat. In addition, the high content of unsaturated fatty acids in fish causes the fish to oxidize easily and result in a rancid odor.
The role of microbial contamination in fish also needs to be considered, as it can cause the fish to decompose quickly. The high water content is very inviting for microorganisms to grow. Microorganisms that grow include: Pseudomonas sp., salmonella sp., and so on.
Storing the fish after capture is also very important. The fish must be stored in the right conditions so that it does not spoil quickly. Storage conditions such as humidity and temperature must be considered. Fish stored in low temperature conditions will affect its shelf life. This is because low temperatures can inhibit the activity of microorganisms and enzymes.
This is the discussion about Fish Growth Phase: Definition, Types, Counting and Factors Hope this review can add to your insight and knowledge, thanks so much for visiting. 🙂 🙂 🙂