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Topmouth gudgeon (Pseudorasbora parva) are a small freshwater fish native to Asia. Read more about this invasive fish.

Topmouth Gudgeon, courtesy of Jack Perks Topmouth Gudgeon, courtesy of Jack Perks

Appearance: topmouth gudgeon have a round elongated body, silver in colour and shimmering purple sides.They have a characteristic up-turned lower jaw and mature males have a prominent hump behind the head.

Typical size: 4-8cm

Lateral Line scale count: 34-38 (this is the dark row of scales along the central length of the fishes body).

Lifespan: 2 to 4 years

Topmouth Gudgeon are a small freshwater fish native to Asia. They have quickly spread through Europe and have been introduced to the UK via the aquatic trade. They are extremely invasive causing great harm to local ecosystems. They breed successfully in large numbers, out-compete native fish and predate on invertebrates and the eggs and larvae of other fish. They are highly territorial, males guard the eggs and have been recorded in densities of 60+ fish per square metre.

Last date edited: 18 September 2015