Leuciscus leuciscus | Dace | Deas



Conservation status

Least Concern

First reported in the wild



Invasive species - risk of Medium Impact

Irish status


Introduction pathways - 1

Release in Nature

Introduction pathways subclass - 1

Fishing in the wild

Invasive score


NAPRA Ireland risk assessed


Species Biology


Slender bodied fish, 20-25cm long, up to 600g; eyes have a distinct yellow iris; pale, or possibly with an orange tint, pectoral, pelvic and anal fins (Welby & Cook, 2004). Eggs salmon pink and stuck to the substrate of shallow, clear, gravelly rivers and streams (Welby & Cook, 2004).


Omnivorous, it has a highly varied diet with larvae feeding on zooplankton and adults feeding on a variety of arthropods, algae, macrophytes and small cyprinids and salmonids (King et al., 2009; Welby & Cook, 2004). Regarded as a pest species in parts of its native range, as it is not considered a good sport or palatable fish (Welby & Cook, 2004). . Competes with salmon for breeding grounds (O'Grady, M. in Caffrey et al., 2007), as well as potentially impacting on populations through predation (King et al., 2009).


Inland surface waters


Communally spawning species, dace spawn in spring (February - early May) when water temperatures reach 8-14°C in gravelly, well oxygenated rivers and streams (Welby & Cook, 2004). Males sexually mature at 2 years of age and females at 3 producing 2,000-27,000 eggs (Welby & Cook, 2004).

Pathway and vector description

Intentionally release in the Blackwater river in 1889, it is possible that the spread of dace has been to flood events washing fish from the Blackwater system into other rivers or dace moving through estuarine waters into other river systems (Caffrey et al., 2007). However, the spread to the rivers Barrow and Nore make it far more likely that dace expansion in recent years is due to deliberate human mediated transfer from one river system to another.

Mechanism of impact

Competition, Predation

Broad environment


Habitat description

Form large active shoals in the upper layers of clean, fast-flowing rivers, though occur in still waters (Welby & Cook, 2004).

Species group


Native region



World distribution(GBIF)

Irish distribution

Established - Localised but spreading. Formerly confined to the Blackwater catchment in Munster, in the 1980 they were reported in Co Clare and by 1990 had entered the Shannon catchment, though the hydroelectric dam at Ardnacrusha may prevent them spreading further upstream (Caffrey et al., 2007).

Native distribution

Native to Europe, including Britain, and parts of Russia, as far east as the Caspian and Black seas (Welby & Cook, 2004).

Temporal change

Date of first record category


Fifty year date category


Records submitted to Data Centre in 2021

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How can you help

Report any sightings to the National Biodiversity Data Centre.



J. M. Caffrey, B. Hayden and T. Walsh (2007). Dace (Leciscus leuciscus L.): an Invasive Fish Species in Ireland. Irish Freshwater Fisheries, Ecology and Management No. 5. Central Fisheries Board, Dublin, Ireland. King, J.L., Marnell, F., Kingston, N., Rosell, R., Boylan, P., Caffrey, J.M., FitzPatrick, Ú., Gargan, P.G., Kelly, F.L., O’Grady, M.F., Poole, R., Roche, W.K. & Cassidy, D. (2011) Ireland Red List No. 5: Amphibians, Reptiles & Freshwater Fish. National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht, Dublin, Ireland. Welby, I. & Cook, I. (2004). Dace Leuciscus leuciscus In: Freshwater fishes in Britain the species and distribution. Davies, C., Shelley, J., Harding, P., McLean, I., Gardiner, R. & Peirson, G. (eds). Harley Books, Essex.

CABI Datasheet

IUCN Red List of Threatened Species

DAISIE Factsheet