Saturday, October 24, 2020
Home Consumer Post Tilapia: the aquatic chicken

Tilapia: the aquatic chicken

Tilapia may be the most popular fish in the Philippines today but our forefathers had never tried it.  Although there are 700 species of tilapia, they are mainly found in Africa and South America.  It was not only in the 1950s that tilapia was introduced in the country.

Today, tilapia farming has considerably contributed to the country’s food security and employment generation.  In the first quarter of 2016, for instance, the Bureau of Agricultural Statistics showed the country produced more than 98 metric tons of tilapia.  About 89.34% were from ponds while the remaining 10.66% were caught in inland municipal fisheries.

According to the Department of Agriculture, the Philippines ranks fourth among countries that produces tilapia; the top three producers are China, Papua New Guinea and Indonesia.  Currently, the country produces about 10% of the total world production of tilapia.

Tilapia has been an important source of food for man at least since recorded history started.  The fish Peter caught in the Sea of Galilee and those with which Jesus Christ fed the multitudes were reportedly tilapia.

Today, tilapia is raised in almost all parts of the world, including the United States, Costa Rica, Mexico, Brazil, Peru, Jamaica, England, France, India, Indonesia, China, Malaysia, Sri Lanka, Thailand and the Philippines.

WIDELY CULTURED

“No fish—with the probable exception of the common carp—is more widely cultured than tilapia,” wrote John E. Bardach, John H. Ryther, and William O. McLarney, authors of Aquaculture: The Farming and Husbandry of Freshwater and Marine Organisms.

It was British naturalist A. Smith who gave the fish its name in 1840.  The word “tilapia” is derived from the African bushmen’s word for “fish.”  According to Ethelwynn Trewaves of the British Museum’s (Natural History) fish section, the natives’ word commenced with a clicking sound that Smith interpreted as “til.”

 

Fishery experts dub tilapia as “aquatic chicken” because it possesses many positive attributes that make the fish suitable for a wide range of aquaculture systems.  For one, tilapia tolerates a wide range of environmental conditions.  For another, it is highly resistant to diseases and parasitic infections.

Other good traits of tilapia include excellent growth rates on a low-protein diet; ready breeding in captivity and ease of handling; and more importantly, wide acceptance as food fish.

But such was not the case in the past.  Tilapia took some time to be accepted as table fish.  Muddy taste, unappealing color, and stories about it being bred in unsanitary waters were among the reasons why tilapia was initially shunned.

PROLIFIC

It was Deogracias Villadolid of the then Bureau of Fisheries (now known as Bureau of Fisheries and Aquatic Resources) who brought some breeding stocks of tilapia from Thailand into the Philippines in the 1950s.  Calling it a “miracle fish,” the bureau wanted it to be raised in backyard ponds nationwide.

But tilapia’s high reproduction rate resulted in overcrowded ponds and stunted fish, and many Filipinos became disappointed over its performance.

The cause of overcrowding was simple.  Pond-reared tilapia, with a natural ratio of 50% male and 50% female, mature in 60 days.  They breed frequently, often every 30 days.  “Female tilapias may spawn from 100 to thousands of eggs, depending on its size,” the Iloilo-based Southeast Asian Fisheries Development Center (SEAFDEC) reported.

At such growth rate, there was more fish in the pond and competition for food escalated.  With reduced nutrition, the best attainable market size for tilapia at that time after four month was only 150 grams.

“Tilapias are prolific,” said Dr. Rafael D. Guerrero III, former executive director of the Philippine Council for Aquatic and Marine Research and Development.

Generally, tilapias spawn in shallow portions of lakes, rivers or ponds.  In breeding, the male builds nests on the bottom to attract females.  The nests are round and shallow, about 20-25 centimeters wide.

Studies have shown that the male tilapia grows faster and bigger than the female tilapia.  The logical choice was to grow all male tilapias.  But could male tilapias be selected and separated from the females?  Was it physically possible to select the fish for stocking in the ponds?  Yes, it could be done—through manual sexing.

In manual sexing, the male is distinguished from the female tilapia by looking at an organ called the urogenital papilla, which is found near the anus of the fish.  There are two openings in the female fish, and only one in the male fish.

“Manual sexing is cumbersome and time-consuming,” said a publication published by the Department of Science and Technology (DOST).  “Sometimes, the openings are not easy to see.  The technique is only 80% accurate because of human error.  Another disadvantage is that you can only sex fish when they are 3 months old. By then, they are almost fully grown.”

TRANSSEXUAL TILAPIA

Dr. Guerrero, who has devoted more than three decades of his life to laboratory and applied science, knew that there was a more practical, effective and economical method of solving the problem.  He studied the work of other scientists and came across the concept of using sex hormones to reverse the sex of fish.

After almost two years of research, he was able to convert all tilapias in a pond to male when fed with a synthetic male hormone—methyltestosterone (a man-made form of testosterone)—for a certain period during the “sexless” stage.

He called it sex reversal technology (SRT).  Today, more than 20 countries around the world are applying the technology commercially.  For his effort, Dr. Guerrero received several citations from different award giving bodies.  In 2004, he was conferred the Mgr. Jan D.F. Heine Memorial Award by the International Tilapia Foundation.

But are sex-reversed tilapia safe to eat?  Dr. Guerrero said the oral treatment with methyltestosterone in tilapia is only for 3-4 weeks during the sexless stage of the fry.  “After withdrawal of the treatment,” he assured, “there are no residuals left in the system of the fish after 92 hours.  Since the fry are grown for at least 3-4 months for market and human consumption, it is very safe.  There can, therefore, be no side effects if there is no synthetic hormone left in the systems of the fish.”

The use of methyltestosterone for tilapia sex reversal is generally accepted throughout the world except in Europe which has a strict organic (no synthetics) policy.  “So far, since its application more than 30 years ago, there is no negative or harmful effect on humans reported,” Dr. Guerrero said.

PINE POLLEN

Meanwhile, a recent study conducted by researchers from the Central Luzon State University has found out that tilapia growers may need not to use the commercial sex hormone if pine trees grow in their area.  The pollen from pine trees may do the same trick.

“The use of pine pollen in its unprocessed condition enables the change of sex of young fishes used for breeding, turning in 84.59-90.46% males,” said Dr. Ravelina R. Velasca, of CLSU’s Freshwater Aquaculture Center, who headed the study.  Unprocessed condition means the pollen still has a protective cover.

“The use of pine pollen technology in tilapia sex change eliminates health hazards associated with all-male tilapia production,” she added.  “It is an environment-friendly approach and could be an alternative to the use of high-priced standard hormone in sex change.”

Pine pollen are the male part of the pine tree.  A raw pine pollen, it has been discovered, contains the richest seedbed of male hormone, the testosterone derived from plants.  “The male and the female reproductive organs are found in the same tree,” Dr. Velasca said.

As much as 90% of the tilapia cultured in the country is sex-reversed, according to Dr. Guerrero III.  “At least 50% of the tilapia produced in the United States, Canada, Israel, the Caribbean and Asia is sex-reversed,” he pointed out.

Nutritionists claim that 100 grams of tilapia provides approximately 93 calories, with one gram of fat (0.5 grams saturated), 55 milligrams cholesterol, 37 grams sodium, 0.5 milligram iron, 19.5 grams protein, and 90 milligrams Omega-3 fatty acids.

Most of the tilapia raised in the Philippines are consumed locally.  Filipinos relish its cotton-like meat and fairly good taste. Both Americans and Europeans are also fond of tilapia since they consider it as “white meat,” a health food low in cholesterol and fat. Also, chefs have a preference for tilapia’s firm meat.

CONTRASTING VIEWS

Contrasting views on the value of tilapia to human health have been reported.

A study done in the United States said that eating tilapia is not good for those with heart problems.  Researchers at the Wake Forest University School of Medicine in North Carolina said “eating tilapia is worse than bacon.”

Dr. Floyd Chilton, a professor of physiology and pharmacology and the director of the Wake Forest Center for Botanical Lipids, told the American media: “All other nutritional content aside, the inflammatory potential of hamburger and pork bacon is lower than the average serving of farmed tilapia.”

Dr. Eliza Mei Perez Franciso, a nutrition support physician at St. Luke’s Medical Center, disagreed with Chilton’s statement on tilapia.

In a magazine interview, Dr. Francisco said that, “tilapia is not necessarily worse just because it contains less Omega-3 than salmon and more Omega-6 than bacon. It still has many nutritional benefits, and cannot be judged solely on its potential to cause inflammation.”

Let’s take a closer look at the comparison.  Tilapia has 26 grams of protein while bacon has a measly 0.07 gram.  Tilapia’s fat content is three grams compared to 100.76 grams for bacon.  In addition, tilapia is an excellent source of phosphorus, niacin, selenium, vitamin B12, and a good source of potassium.  Bacon, on the other hand, contains 1,000 milligrams of sodium, 166 milligrams of cholesterol, and enough possible carcinogenic nitrites to make pregnant women think twice.

Francisco urged Filipinos not to give up tilapia, particularly those raised in ponds, completely. “Continue to eat fish regularly, at least twice a week, and combine tilapia with Omega-3-rich fish (like tuna, salmon, and mackerel) for a more balanced mix of fats.”

Tilapia chicharon

Instead of frying tilapia, she recommended that you grill, boil or steam the fish.  “This will help you cut down on total fat in the diet.”  But if you want to fry or sauté it, use canola or olive oil.  Or cook in coconut milk (as in ginataang tilapia).

Tilapia has very low levels of mercury because it is a fast growing- and short-lived fish that mostly eats a vegetarian diet.

OTHER BENEFITS

But there’s more to tilapia than just providing food.  In the United States, tilapias are stocked in the canals that serve as the drinking water sources for the cities of Phoenix, Mesa, and others. The fish reportedly help purify the water by consuming vegetation and detritus, thus greatly reducing purification costs.

Tilapia also serves as a natural, biological control for most aquatic plant problems. Tilapia consumes floating aquatic plants, such as duckweed watermeal, the most “undesirable” submerged plants, and most forms of algae.

In Thailand, tilapia is becoming the plant control method of choice in reducing, if not eliminating, the use of toxic chemicals and heavy metal-based algaecides.   In Kenya, tilapia helps control malaria-causing mosquitoes.  Tilapia consumes mosquito larvae, which reduces the numbers of adult females, the disease’s vector. G

LEAVE A REPLY

Please enter your comment!
Please enter your name here