Most Unwanted: Topmouth gudgeon
Pseudorasbora parva
Habitat: Freshwater
Threat: Competes with native fish species and known to affect ecosystem functioning
Status: Potential
The Topmouth Gudgeon has been found a number of rivers and lakes in England and Wales. This species while only being 3 – 4 cm long can have a devastating impact on native fish species communities.
What is it
This is a small fish species that resembles the native gudgeon except in that its mouth is pointed upwards, allowing the species to feed on the surface of the water.
Impact
The species can severely impact on other fish species by eating their eggs. However, this species is known to have a breeding rate that is four-times faster than native fish and is a carrier of a parasite, similar to, or possibly the same as, a disease called the ‘rosette agent’. Topmouth Godgeon are also known to impact on plant community dynamics leading to algal blooms.
Where is it from
South East Asia
Where is it now
The species has invaded lakes in England and Wales and the Environment Agency has implemented control measures.
How can it get here
Escape from aquaria trade.
Deliberate introduction as fish bait.
What you can do
Don’t dispose of aquaria material near a pond, river or waterbody.
Don’t introduce fish species.
Don’t introduce fish species from areas currently infested with TMG as the possibility of contamination is very high.
Report all sightings.
Additional reading
Habitas Invasive Alien Species in Northern Ireland
