Vol. 5 Num 541 Sun. December 04, 2005  
Front Page

Catfish threatens local species
Sewers become breeding ground

A carnivorous alien species of African catfish is spreading in the natural eco-system of the country, posing a great threat to other local and indigenous fish species of the country.

In Dhaka City, people often capture catfish from different ditches and the sewerage system, suggesting the catfish has been slowly spreading there. Raising the issue again, a large catfish was caught from the Baitul Mukarram mosque pond a few days ago.

Last year, experts expressed their concern when a 20-kilogram catfish was caught from a sewerage line of the Panthapath. Sewer cleaners who killed the huge catfish claimed there were more African catfishes in the sewers, hinting that the sewerage system might have become a home to the species.

While the impact of other alien fish species seems to have been negligible, the African catfish noticeably wiped out indigenous fish populations in ponds and water bodies where it lived. Some fish farmers complain African catfish are harmful because they destroy all other species living with them.

"It is a active predator in the true sense. It eats up all the small fishes in the pond, even the frogs are not spared," Dr. Muhammed Shafi, a prominent fish expert of the country, said in his book, "Bangladesh Fisheries". If this catfish becomes successfully establishes itself in nature, the existence of small fishes are endangered, he added.

Ironically, officials of the Fisheries Department brought the African catfish to Bangladeshi waters. It was one of 14 fish varieties introduced by authorities since 1953.

"Now we are not encouraging them. It was banned a few years ago by a notice of the department of fisheries but the government can not take any legal steps if someone cultivates it," said Mohammed Shahidul Islam, deputy director of the Aquaculture section of the department of fisheries

In a shocking incident in 2003, African catfish killed the three-year old son of a farmer in Mymensingh, 120 kilometres from Dhaka, when the toddler was playing in the shallow waters of a pond, several newspapers reported.

"We have heard the African catfish has cut off the private parts of some children around the country as they were taking a bath in the pond where the catfishes were cultivating," said Mohammed Shahidul Islam.

As Bangladesh is a flood prone country, the government should have taken a clear-cut policy before introducing such carnivorous species, experts say, adding that the catfish will eat out all other fish species if it spreads to rivers or other wetlands.

Some experts disagree, however. Shahidul Islam thinks if the African catfish spread outs in the natural water bodies, other carnivorous species like Boyal, known as fresh water shark, will wipe them out.

In the low-lying outskirts of Dhaka, African catfish are being cultivated in specially constructed tubs or submerged bamboo cages in ponds. According to cultivators, they supply up to 3,500 kilos of catfish to the capital and its suburbs from 200 such farms.

During floods, the fish spread out from the farms and rehabilitate in the sewerage system and different ditches in the city.

"They multiply fast, are possible to cultivate even in the most contaminated water and will feed on whatever you give them," said Abdur Razzak, the caretaker of one of the biggest African catfish cultivators, Kalam Mia's firm.

The African catfish can rapidly multiply within just two months, which makes them popular among catfish cultivators.

A giant catfish recently caught at a pool in a construction site in the city. PHOTO: STAR