Drawing his web on the banks of river Vaigai at Kochadai in Madurai, P Karuppu, an inland fisherman, is visibly upset. In his web are 40 massive darkish and closely scaled suckermouth catfish, together with a number of smaller fish. âNobody eats this fish,â says the fisherm an from Thuvariman village. âHowever they're consuming into our livelihood. â
Suckermouth catfish (Pterygoplichthys) are extra generally often known as âtank cleanersâ as a result of they're utilized by decorative fish fanatics in aquariums. Out within the open waters although these fish are rising to massive sizes and have grow to be invasive throughout the river methods of Tamil Nadu, particularly within the Cauvery, the Vaigai and the Thamirabarani.
Karuppu remembers catching fish like rohu, katla and tilapia in massive numbers in Vaigai as much as 5 years in the past. As we speak, their catch consists principally of suckermouths that are inedible. âItâs getting worse by the 12 months. Different species are disappearing from the river,â says R Anbu, Karuppuâs fishing companion.
Fishermen from the Kollidam and Cauvery river banks recall catching quite a lot of carp like âaathu kendaiâ and âbhavani kendaiâ (river carps), viral ( murrels) and jilebi (tilapia). As soon as ample, these fish species have disappeared at alarming charges, changed by suckermouths. âAathu kendai was one of the crucial sought-after fishes in Trichy. We hardly catch them in our nets at the moment,â says M Muthuveeran, a fisherman from Thirupazhthurai close to Grand Anaicut in Trichy.
The heavy-finned fish additionally destroy the nets of fishermen. If a dozen are caught within the web, it must be torn. Cauvery and Kollidam fishermen say the 2005 Cauvery floods introduced these fish in troves.
Professor S Chandrasekaran, an invasion ecologist from the plant sciences departm ent of Madurai Kamaraj College and his workforce of students R Mohan Raj and R Indhar Saidanyan, who've been learning this species throughout the state, say the Cauvery and Vaigai river basins are the worst affected.
âCompletely, 26 websites comprising dams, lakes, ponds, canals and tributaries of the Cauvery and Vaigai river basins in Trichy, Thanjavur, Theni, Madurai and Sivagangai have been recorded for the huge distribution of the sustained inhabitants of tank cleaner fishes.
Their inhabitants was recorded to be ample within the sewage-contaminated websites ofthe Cauvery and Vaigai river basins,â says Mohan Raj. Although not carnivorous, the catfish are prolific breeders reproducing around the 12 months, with every feminine spawning 7,500 eggs each time.
The researchers additionally discovered that the male digs burrows on the banks for the feminine to soundly deposit the eggs whereas they guard the nests. âWe now have documented the burrows although we've got not seen the males guarding them as a result of the turbidity is excessive in our rivers,â says Chandrasekaran.
A backside dweller and nocturnal in nature, the suckermouths donât get caught in nets when there may be ample water. The issue begins as soon as the water degree begins depleting. âThe intensive buying and selling of unique fish and the irresponsible behaviour of pet keepers of releasing them within the wild have triggered this menace,â says Chandrasekaran.
After their examine appeared in Present Science Journal in 2017, these researchers obtained a consultancy mission from the state planning fee to check the eco-socio-economic impacts of the species in Tamil Nadu. However issues haven't moved additional. A senior official from the inland fisheries division headquarters in Chennai says there may be nothing on the coverage degree to deal with this invasive fish menace within the water our bodies of Tamil Nadu.
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