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What’s fishy about tilapia

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Tilapia is a tropical freshwater fish that is endemic to Africa and the southwestern Middle East. Red-bellied tilapia, Blue tilapia, Nile tilapia and Mozambique tilapia are among the most common species used in aquaculture.

The tilapia fish ranges from 6 to 28 cm in length, weighs about 4 kilograms, and does not live more than nine years. Some people prefer it due to its delicious taste and many nutrients beneficial to human health.

Since the thirties of the last century, tilapia fish of all kinds have been imported and spread all over the world for the biological control of unwanted aquatic plants and to eliminate mosquito larvae and use them as bait for some fisheries and as ornamental fish.

It has also been recently promoted as a food and an essential source of protein that can provide food security for developing countries. Due to their extreme tolerance to different and harsh environmental conditions in fresh water and their high tolerance to salinity, in addition to their high reproductive and growth rates and their ability to resist diseases, tilapia fish are very suitable for aquaculture and rapid economic returns.

However, the results of the joint consultative research between Sultan Qaboos University and the Iranian University of Shiraz on Omani freshwater fish confirmed that the biological diversity of local fish is in danger of total disappearance, and the reason is due to the introduction of tilapia fish in the waters of the Sultanate of Oman for one reason or another.

The joint research, funded by Al Mawarid Geological Consulting Company, confirmed that bringing tilapia out of its habitat and inserting it into natural open water bodies in particular, has caused many major environmental problems around the world, threatening local habitats and the diversity of surrounding aquatic organisms, especially local fish, quantities and even their sizes through unequal competition for food, housing or habitat.

This is because tilapia fish is a very aggressive fish despite its beautiful and attractive shape. It also caused the destruction of habitats by introducing diseases and parasites genetic pollution of some local fish, which caused the disappearance of some local species. Thus, tilapia specialists have concluded that despite the potential or perceived economic benefits to human society in an enclosed environment, “their cultivation or dissemination in open freshwater is an ecological disaster for native fish and biodiversity”.

The research indicated that non-native Nile tilapia, and perhaps its hybrid species or subspecies, were introduced to the natural waters of the Sultanate of Oman (wadis and water springs) to control mosquitoes in the early nineties of the last century. Through field visits to many Omani valleys and water springs, the researchers found that this guest has become the dominant species and has reduced the number of local fish in terms of size, number and type.

“There are valleys where it has become very rare to see local fish’’, according to the research. On the other hand, the fish diversity is more noticeably in the valleys and springs that tilapia has not yet reached.

“And if the reason for bringing in tilapia fish is to prey on mosquito larvae and reduce the spread of malaria, there are researches that indicate that the Omani locally called “sad” fish also attacks mosquito larvae with the same efficiency’’, according to the researchers.

The study recommended that the use of open freshwater should be prohibited for tilapia culture. It also recommended that unwanted tilapia fish should not be disposed of in valleys and stagnant waters and that the import of tilapia fish as ornamental fish should be restricted.

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