Tilapia

Tilapia is a kind of fish that belongs to the family Cichlidae and order Perciformes. The tilapia fish is the native bread of Africa and are mostly the freshwater fish. The tilapia fishes are the one of the easily raising and harvesting food fish. So, the red tilapia fishes have many commercial advantages including fast growth, resistance to disease, cheap food cost as they include abundant algae and zooplanktons in their diet. In the early Egyptian civilization, the tilapias are grown in the warm water aquaculture system. Later, they introduced the Mozambique tilapia fishes into the freshwater habitats. In many parts of the world. World wide widely cultures and introduced species in the Tilapia fishes is Oreochromis niloticus.

All the species of tilapias were formerly kept under the genius Tilapa. Later the tilapia fishes are grouped into two diverse groups based on mouth-brooding genera. They are Sarotherodon and Oreochromis. The matured eggs from the tilapias are deposited in the bottoms of ponds and lakes 

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Characteristics of Tilapia

Physical Appearance of Tilapia

The species in Tilapia family have laterally compressed deep bodies. Like other cichlids species, they have lower pharyngeal bones, which are fused into a single tooth-bearing structure. A complex set of muscles of chitralada tilapia allow the upper and lower pharyngeal bones to use as a second jaws for processing their food. They are allowing a division of labour between the true jaws and the pharyngeal jaws. This shows that the red tilapia fishes are efficient feeders, which can capture and process a wide variety of prey. The mouth of blue tilapia fishes are protrusible, which means, they can bordered with wide and often swollen lips. The jaws of tilapia contains conical teeth. Further, tilapia fishes have a long dorsal fin, and a lateral line that often breaks towards the end of the dorsal fin, and starts again after the two or three rows of scales. The Nile tilapia fishes can grow upto the length of about 2 feet. 

The Tilapia fishes are temperature-sensitive species, but they can adapt for a wide range of temperature conditions. A small example for their temperature sensitivity is, while they are introducing into the Salton sea, they can live and merged and living with other species. But the other fishes may face difficulty to survive in salt water.  

Habitat of Tilapia 

The species of Tilapia fishes can found in salt water, rivers, lakes, network of canals and ditches in farming lands. They are often stocked in the canals and artificial lakes for controlling the algae, unwanted weeds and insects. Some isolated population of tilapia fishes are existing in the Salt River lakes, Alamo Lake, Lake Pleasant, and Roper Lake. The mortality rate of tilap may rise, while exploring them for prolonged winter ot the temperature below 50 degrees Fahrenheit.

Reproduction of Tilapia

Tilapis fishes are the internal live bearers. They are also known as the mouth brooding species, which means they can carry their fertilized eggs and lay the young fishes from their mouth. After few days of birth, the yolk sac of fries get absorbed. Only female fishes take part in incubating eggs inside the mouth and remains undisturbed for 1 week. The male fishes will get detach themselves from the young fries or eggs. But the  Zilli’s tilapia, a species of tilapia, both the male and female fishes together build their nest and guard their eggs and young fries.  The young fries can mature between the age of about three to six months. Usually the spawning occur in the matured fish when the water temperature reaches about 68 degree celsius.  

Food for Tilapia

Tilapia is an omnivorous species, which can take small fishes, insects, worms, shrimps, larval fish, detritus, decomposing organic matter, and other small aquatic living organisms. But their includes algaes and aquatic plants in their diet. Tilipia fishes are considered as the filter feeders because they are  harvesting plankton from the water. So, many people using them as weed controller in the lakes, river, canals...etc. 

The natural food organisms are preferable foe fishes to reach about 30 to 50 percentage of their maximum growth. The tilapia fishes do not have ability to physically filter the water through gills like other true filter feeders such as gizzard shad and silver carp. The chitralada tilapia  gills will secrete a mucous substance to trap plankton. The plankton rich mucous, or bolus secreted by fishes will swallow by themselves. The range of digestion and assimilation of plant materials by the tilapia fishes are depends on their length of the intestine

According to the this, the Mozambique tilapia species are the less efficient harvester than the Nile or Blue tilapia species. 

The red tilapia fishes will physically grind the plant tissues between two pharyngeal plates of fine teeth. The pH of tilapia’s stomach is below 2 so, they can ruptures the cell walls of algae and bacteria. The fishes in the cultured form can digest 30 to 60 percent of the protein in algae. They can digest blue-green algae efficiently than green algae.

While feeding the supplement nutritions, they do not disturb the pond bottom as aggressively as common carp.  But they can effectively browse their feeds on live benthic invertebrates and bacteria-laden detritus. The tilapia species are not a piscivorous, but their juveniles may consume larval fishes. 

Even while farming tilapia fishes in artificial ponds, they require sufficient nutritional value from the natural foods. The heavily weeded ponds with little or no water exchange, natural food organisms all together will provide one-third or more of total nutrients for the growth of fishes. The tilapia fishes can also digest the animal protein, similar to the catfish. But they are more comfortable for the digestion of plant protein, especially more fibrous materials.

Like other warm water fishes, tilapia also requires some amount of amino acids. They require protiens for the maximum growth and  function of protein quality and fish size and have been reported as high as 50 percent of the diet for small fingerlings. The digestible energy requirement for tilapia fishes is about 8.2 to 9.4 kcal per gram of dietary protein, which is similar to dietary energy requirement of catfish. 

Angling Methods 

The best season for catching the tilapia fishes through angling method is warm months. Can use small worms, crickets and dough balls on small hooks for angling the fishes. Usually, the catching the tilapia fishes are difficult and need extreme caution. The tilapia fishes are most aggressive during the spring and spawning periods. To catch the tilapia fishes, in addition to angling method can use bow and arrow, crossbow, snare, gig, spear and speargun methods. 

Requirement of Artificial Tilapia Pond 

Tilapia is one of the tolerant species, they are commonly freshwater fish but they can survive in salinity, high water temperature, low oxygen content and high ammonia concentrations. So, cultivating tilapia fishes in the artificial ponds are not so risky like other species. 

Water Salinity 

All the species of tilapia are tolerant to the brackish water. But the nile tilapia species have less saline tolerance, even they can grows well at salinities up to 15 ppt. The Blue tilapia species can also grows well in brackish water with the salinity range of about 20 ppt. The Mozambique tilapia species can grow well with highest salinities even in the full strength seawater. So, the Mozambique tilapia and some mossambicusderived red tilapia species are more preferable for the saltwater culture. Some times, their reproduction capablity gets decline in the water salinities above 10 to 15 ppt. The blue and nile tilapia fishes can reproduce in saline water up to 10 to 15 ppt, but they can show best results in the saline water below 5ppt. 

Water Temperature

Usually, the tilapia fishes are the warm temperature fishes, so they cannot tolerate the low temperature. The tilapia culture is not suitable for the temperate regions. Most of the Tilapia species can not withstand more than 50 to 52oF.  But the blue tilapia species can tolerate the temperature upto 48o F.  

Usually, the tilapia species stop acquiring their feeds, when the water temperature falls below 63oF.   The temperature  higher than 80oF is for the reproduction of tilapia species, but it is not possible to occur below  68oF. During the cold season of subtropical regions, the number of fry production will usually declines, when the average temperature of water is less than 75oF. During the warm period, well matured tilapia can lay up to 600 fries, but during the winter season the count of tilapia fry laying may fall below 250. So, the preferable water temperature for tilapia growth is about 85 to 88oF. The growth rate in preferable temperature is three times more than that of  72oF.

Dissolved Oxygen Concentration

Tilapia fishes can survive in the water with the concentration of dissolved oxygen less than  0.3 mg/L, which is considerably low level than other cultured fishes tolerance limit. According to the research study, the Nile tilapia fishes can grow better in aerator tanks, through which we can  prevent morning DO concentrations from falling below 0.7 to 0.8 mg/L. The growth of tilapia fishes will get inhibited when they get additional aeration with the dissolved oxygen concentrations above 2.0 to 2.5 mg/L.  Even the tilapia can survive in the acute low dissolved oxygen concentrations for several hours, but the artificial tilapia ponds should be managed to maintain dissolved oxygen concentration of above 1 mg/L. Metabolism, growth and, possibly, disease resistance of the chitralada tilapia will decline when concentration of dissolved oxygen  falls below the level for prolonged periods. In general, tilapia fishes can survive in water pH ranging from 5 to 10 but they can show best results in the water containing pH range of 6 to 9.

Ammonia

When the tilapia fish are suddenly transferred into the un-ionised ammonia concentrations greater than 2 mg/L, the mortality rate of chitralada tilapia will increase. While gradually facing the un-ionised ammonia concentrations up to 3 mg/L, these fishes will manage to survive for 3 to 4 days. 

The prolonged exposure to un-ionised ammonia concentration greater than 1 mg/L may leads to decrease the dissolved oxygen concentration in water, which are not suitable for development of Tilapia. Sometimes it may cause death of fry and juveniles in water. Un-ionised ammonia in the water may suppress the food consumption at concentrations as low as 0.08 mg/L. The first mortality of fishes may occur, while prolong exposure may begin at concentrations as low as 0.2 mg/L. 

Nitrite

Nitrite content in water may cause toxic to many fishes.  Because they creates haemoglobin to transport less oxygen further the chloride ions reduce the toxicity.  But the Tilapia fishes have more tolerance to the nitrite than many cultured freshwater fish. Generally, the nitrite concentration should be kept below 27 mg/L for all the freshwater culture. In order to safeguard the fishes against nitrite toxicity in recirculating systems, chloride concentration are often maintained at 100 to 150 mg/L chloride.