Taxonomy
Leuciscus leuciscus | Dace | Deas
Distribution
Status
Conservation status
Least Concern
First reported in the wild
1889
Invasiveness
Invasive species - risk of Medium Impact
Irish status
Established
Introduction pathways - 1
Release in Nature
Introduction pathways subclass - 1
Fishing in the wild
Invasive score
17
NAPRA Ireland risk assessed
No
Species Biology
Identification
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).
Ecology
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).
Habitat
Inland surface waters
Reproduction
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
'In 1889 British anglers river fishing on the Munster Blackwater accidentally released a number of dace and roach (Rutilus rutilus L.), which were being held as live baits. This was the first introduction of both species to the country' (Caffrey et al, 2007). It is possible that the spread of dace has been due 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
Freshwater
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
Vertebrate
Native region
Europe
Distribution
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
Pre-1900
Records submitted to Data Centre in 2025
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How can you help
Report any sightings to the National Biodiversity Data Centre.
References
Publications
Caffrey, J. M., Hayden, B. and Walsh, T. (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.