Redside dace (Clinostomus elongatus)

Synonyms: Luxilus elongatus
GenusClinostomus (1)
SizeLength: up to 12 cm (2)

The redside dace is classified as Least Concern (LC) on the IUCN Red List (1).

A colourful freshwater fish of North America, the redside dace (Clinostomus elongatus) is a relatively small species, recognised by the red stripe extending along the front half of its body. This stripe is bordered above by a second bright yellow stripe, which extends almost to the tail fin. During the breeding season, the colours of the redside dace intensify, while small tubercles also grow over much of the body (2) (3). 

The redside dace has a rather flattened body, with a downward-curving lateral line. The mouth is large, with a protruding lower jaw, making this fish well suited to catching flying insects (2) (3). It is very similar in appearance to the rosyside dace (Clinostomus funduloides), but has a longer, more pointed snout, a more slender body, brighter red on the underside, and smaller scales (4).

The redside dace has a discontinuous distribution, with populations scattered across the eastern United States and southern Canada. It occurs in the Lake Erie and Lake Ontario drainages of south-eastern Michigan, Ontario, Ohio, Pennsylvania and New York, as well as the upper Ohio River basin, the upper Mississippi River basin of Wisconsin and south-eastern Minnesota, and the upper Susquehanna River drainage of New York and Pennsylvania (2) (3) (5).

The redside dace is typically found in pools and slow-moving areas of small streams and headwaters of river systems. These habitats typically have gravel, sand, cobble or bedrock bottoms, as well as overhanging vegetation and an abundance of woody debris. During the breeding season, this species spawns in pools with clean, rocky bottoms (2) (3).

The redside dace is active during the day, when it swims in small schools (6). It feeds primarily on insects, the large mouth enabling it to catch flying insects after a leap from the water (3). 

Spawning occurs in late May, when the water temperature is around 18 degrees Celsius. The female redside dace moves towards a spawning area over gravel at the head of riffles, which is defended by a single male. Between 400 and 2,000 eggs are deposited in the substrate, and are fertilised by the male. The young fish grow rapidly, reaching a length of around 2.9 centimetres by October (3). The redside dace typically breeds at three years of age or older, and lives to around four years old (7).

Due to its fragmented distribution and restriction to a specific habitat, the redside dace is highly vulnerable to local extinctions caused by disturbances to its habitat. Habitat loss and degradation due to urban and agricultural development has resulted in many cool, shaded streams, which this species favours, being converted to warm, unshaded, turbid waters, making them unsuitable for the redside dace (3). Altering stream flow can also result in the removal of streamside vegetation, which this species needs for cover and food (2).

As the greatest threat to the redside dace is habitat loss and degradation, the conservation priority for this species is the protection and management of suitable stream habitat. Degraded habitat still supporting populations should also be restored. The redside dace would also benefit from further surveys aiming to establish if additional populations exist (3). 

The redside dace is classified as Endangered in Ontario (2).

Find out more about the redside dace:

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:

  1. IUCN Red List (August, 2013)
  2. Ontario Ministry of Natural Resources - Redside dace (July, 2011)
  3. Michigan Natural Features Inventory - Redside dace (July, 2011)
  4. Page, L.M. and Burr, B.M. (1991) Peterson Field Guide to Freshwater Fishes, Second Edition. Houghton Mifflin, New York.
  5. U.S. Geological Survey - Redside dace (July, 2011)
  6. Cornell University - Redside dace (July, 2011)
  7. Werner, R.G. (2004) Freshwater Fishes of the Northeastern United States. Syracuse University Press, New York.