Rearing the African black devil

Biodiversity

The African catfish introduced on the sly into the State’s freshwater bodies has proven detrimental to the indigenous small and medium sized fish. Breeding, rearing and selling of the aggressive fish is an offence punishable under our laws, says Rajesh Shrivana.

This is not just any fish. This is the Black Devil of the Freshwaters! This foreign invader of African origin has illegally entered our freshwaters, destroying entire schools of indigenous small fish, causing untold harm to other aquatic organisms including fish.

The invader is the African catfish, also known by the scientific name Clarias gariepinus. This aggressive, carnivore hunter fish is known as mugudu in Tulu. We have an indigenous mugudu known as the Asian catfish (Clarias Batrachus). The Asian catfish and the African catfish are poles apart in terms of size, colour and behaviour. The local fish does not grow to the size of the African fish. Nor is it harmful like the intruder.

The African catfish is a powerful carnivore that swallows everything that comes its way. It grows into a huge fish with substantial weight in a very short time. If by any chance, a small child or dog were to fall in the fish’s tank, they will be gone in seconds! The invader rips the flesh like a shark before swallowing, earning the dubious sobriquet Black Devil! This devil, with its wide mouth easily swallows whole schools of indigenous small and medium-sized fish to satisfy a voracious appetite. Therefore, rearing and sale of this fish is banned in India.

Experts believe that the African catfish entered India from Bangladesh during the end of the previous century, albeit on the sly. In just about 10-15 years, the fish has expanded its presence in most of the states including Karnataka. It’s being said that the invader entered Karnataka along with the fish seed that came from Andhra Pradesh and West Bengal.

The African catfish is popular in several states, including Punjab, Uttar Pradesh, West Bengal, Andhra Pradesh, Odisha, Bihar, Karnataka, Assam and Kerala, mainly because it is a profitable business. It is estimated that 16 per cent of a day’s catch in the Yamuna river belongs to the African invader which weighs one to two kg. The young ones of this fish are also finding their way into other states via West Bengal. Indeed, most farmers are deliberately selling this foreign fish, claiming it to be the indigenous Asian catfish.

Rearing of the African catfish has thrived on the outskirts of Bangalore and Mangalore and in Kolar, Hassan and Tumkur. The foreign invader has been spotted in the Hemavathi Reservoir in Hassan district and in Nethravathi and Gurupura rivers of Dakshina Kannada district as well.

These fish, weighing up to five kg, have found their way to the market near State Bank, Mangalore. They have been spotted in Kasargod of neighbouring Kerala as well. Entering our rivers and streams and decimating the aquatic life is a matter of concern, as we may soon lose what’s left of our fish wealth.

The African catfish’s body is black and the fish sports four pairs of barbels around its mouth just like a cat, justifying the name. The colour makes the fish extremely difficult to spot. It is also very difficult to maintain a hold of its slippery body. Come rains in May-June, these fish rush towards paddy fields to lay eggs, braving floodwater even. Some people who wait for this phenomenon, light torches and catch the fish during night.

Those involved in rearing the African catfish around Bangalore throw dead poultry, dead dogs and waste from the abattoirs to the fish as food. Following complaints from locals and other farmers, authorities have destroyed hundreds of catfish ponds in the last six months.

Yet, the African invader is a tough customer. The fish gets oxygen directly from the air despite lack of water and manage to survive in turbid tanks. These fish are also known to live for a few hours after getting out of water, crawling for some distance! It is this ability to survive that has helped the African catfish succeed in the survival game, says fisheries scientist Dr N Basavaraj of the Fisheries College, Mangalore.

Because of its ability to grow faster and heavier, the African catfish was a hit among farmers, initially. But the method involved in its rearing, its food habits and a few other social factors led to its decline in popularity. Throwing dead animals as food disgusted fish lovers and farmers. It was found to be not viable economically as well. Experts are now discussing the consequences of this development and it is hoped that a solution will emerge soon.
(Translated by B S Srivani)