British Waterways is today asking the green-fingered to be aware of the Dirty Dozen lurking in and around their garden ponds and in their fish tanks.

Often attractive ornamental aquatic plants and sometimes animals bought as pets or introduced unwittingly into our waterways. The Dirty Dozen are all invasive species introduced from overseas which can quickly choke canals and rivers and cause extensive harm to native wildlife.

Although introduced to the waterways by well-intentioned members of the public, the Dirty Dozen can quickly takeover, are often costly to remove and can decimate some of the nation’s best loved waterway creatures.

Chris John, British Waterways national ecologist, explains: “In their native countries these particular species are kept in check by nature, where they are part of an adapted system of predators. However, here they have no natural predators and so often quickly outcompete other plants, animals and fish, causing serious problems for wildlife, as well as choking up boats, the towpath and other 200-year old heritage structures such as locks and bridges.”

The Dirty Dozen have all been introduced to Britain’s canals and rivers from overseas, having made their way to our waters in many ways. Often, unaware of their potential to cause damage, people introduce species intended for garden ponds and aquariums to their local canal when they dispose of them, for example, throwing weed from fish tanks into canals or releasing Red-Eared Terrapins that have grown too big.

The Dirty Dozen plants and animals are:

• Japanese Knotweed

• Australian Swamp Stonecrop

• Giant Hogweed

• Himalayan Balsam

• Water Fern

• Floating Pennywort

• American Signal Crayfish

• Zebra Mussel

• Zander

• Mink

• Red-eared Terrapin

• Chinese Mitten Crab

Chris continues: “The destruction of suitable places for wildlife to live is the biggest threat facing Britain’s nature today, these species add to this problem by taking more than their fair share of space, water and sunlight. I am therefore asking people to help us by disposing of these plants and animals safely and carefully selecting alternative plants for their gardens, ponds and aquariums.”