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Cat in the water - Aggressive catfish threatens Hesse's ecosystem!
The invasive black catfish threatens native species in the Lahn-Dill district. Pond emptying and fishing operations are ongoing.
Cat in the water - Aggressive catfish threatens Hesse's ecosystem!
There is currently a worrying problem in Hesse: the invasive black catfish, an aggressive fish from North America, has been spotted in the region. This species, which was added to the EU's list of invasive alien species in 2022, threatens native fish species through its violent feeding behavior, which endangers spawn, larvae and juveniles. Their rapid growth and ability to adapt to low oxygen levels and high temperatures make them a serious food competitor for native species. Stern reports that the catfish stir up bottom sediments and thus put a strain on the sensitive ecosystems.
The situation is made particularly explosive by the discovery of black catfish in the Uckersdorf quarry lake near Herborn, after which the Technical Relief Agency (THW) has been pumping out the lake since November 21, 2024. The measure aims to prevent the spread of this invasive species, as it has no natural predators in Central Hesse and could potentially reach the Dill and then the Lahn via streams during floods. The lake, which is only fed by rainwater and has no natural water supply, already poses the risk of an overpopulation of catfish, as around 62 animals have been caught since the start of the campaign and a total of around 100 catfish are expected.
Saving native species
The consequences of the catfish discovery are far-reaching. In order to help the native species, they are relocated to other bodies of water. There was also the positive discovery of an endangered population of noble crayfish in the quarry lake, which now has to fight against raccoons, signal crayfish and crayfish plague. The regional council has already warned: Anyone who abandons animals without the necessary authorization will face a fine. In view of the increasing spread of animal and plant species, citizens must be vigilant and report catfish discoveries immediately. This can be done easily via the online portal of the Hessian State Office for Nature Conservation, Environment and Geology (HLNUG), provided photo evidence is available.
However, combating this harmful species is difficult. Electrofishing and other methods cannot capture all individuals, which is why temporarily draining ponds is being discussed as a recommended measure. A pond in Herborn was successfully emptied last year, with around 100 catfish and over 200 other fish being fished out and moved to other ponds. Still, questions remain as to exactly how the catfish arrived in the region—experts fear they may have been illegally released.
The spread of black catfish is an alarm sign for biodiversity in Hesse. It remains to be seen how successful the current measures to combat this invasive species will be and whether the delicate balance of local waters can be secured in the long term.