Bluebarred pygmy sunfish (Elassoma okatie)

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Male bluebarred pygmy sunfish
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Bluebarred pygmy sunfish fact file

Bluebarred pygmy sunfish description

KingdomAnimalia
PhylumChordata
ClassActinopterygii
OrderPerciformes
FamilyElassomatidae
GenusElassoma (1)

The bluebarred pygmy sunfish is a striking fish, despite its small size, and is named after the male’s eye-catching iridescent blue stripes (2). Both the male and female bluebarred pygmy sunfish have conspicuous dark, vertical bands along the body (2), but while the males are coloured a brilliant iridescent blue between the bands, the females are a much more drab beige (3). The rest of the body is blue-grey to black in males, depending on reproductive activity, and pinkish-brown in females (3). In addition to having a slightly longer body, the male also has longer pelvic, pectoral and dorsal fins than the female (2).

Species in the genus Elassoma are known as pygmy sunfishes because they were originally thought to belong in the same family as other sunfishes, the Centrarchidae (4). However, they are now considered sufficiently distinct to be classified in their own separate family, the Elassomatidae, and some claim they are not closely related to other sunfish at all (5). The family and generic name derives from the Greek words ‘elasson’, meaning ‘smaller’, and ‘soma’, meaning ‘body’ (6). The specific name of the bluebarred pygmy sunfish derives phonetically from the local Indian words ‘oka’, meaning ‘water’, and ‘ateeh’, meaning ‘coming from’ (2).

Size
Male length: 21.2 mm (2)
Female length: 21.0 mm (2)
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Bluebarred pygmy sunfish biology

Relatively little is known about the biology of the bluebarred pygmy sunfish. Spawning occurs from late February to March (3), and most individuals do not live longer than one year (3). The diet of pygmy sunfishes typically consists exclusively of larger-bodied invertebrates (5).

Pygmy sunfishes display intriguing and relatively complex reproductive behaviour (7). Reproductive males aggressively defend a territory using what has been termed the ‘sidling threat’ display. The defending male swims close to the intruder, rapidly beating his caudal and pectoral fins while intensifying in colour, and if necessary will strike rapidly at the intruder. The even more bizarre ‘wiggle waggle’ display is performed by the reproductive male to entice a mate. On approach of a reproductive female, the male swims in an undulating path towards the potential spawning area, fluttering the dorsal and anal fins and alternately extending the pelvic fins. If the male is successful in attracting the female, the female will position herself amongst the vegetation, where the male aligns himself at her side and the eggs and sperm are released; the resulting fertilised eggs stick to the vegetation in small clusters. After spawning, the protective male chases the female away from the eggs, leaving the male responsible for defending the vulnerable brood until hatching, which occurs after several days (7).

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Bluebarred pygmy sunfish range

The bluebarred pygmy sunfish has been found at only four sites, all in the south-eastern United States: the Lower Edisto, New and Savannah River drainages in South Carolina (2), and Fort Gordon in Georgia (3).

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Bluebarred pygmy sunfish habitat

The bluebarred pygmy sunfish is most commonly found in shallow, slow-flowing water with dense aquatic vegetation and a soft substrate rich in decaying organic matter (2). Typical habitats include roadside ditches and ponds (2).  Despite its limited range, this species can tolerate a range of water temperatures (10 to 32 ºC) and acidities (pH 4.5 to 7.5) (2).

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Bluebarred pygmy sunfish status

Classified as Vulnerable (VU) on the IUCN Red List (1).

IUCN Red List species status – Vulnerable

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Bluebarred pygmy sunfish threats

The close proximity of the majority of known populations to roads makes the bluebarred pygmy sunfish particularly vulnerable to human-caused disturbance and pollution (2). Populations near industries such as paper mills and concrete factories are particularly vulnerable to pollution and sedimentation, which may have been responsible for local extinctions in the past (3). Drought is also likely to pose a significant risk, given that populations predominantly occur in shallow, isolated water bodies (8).

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Bluebarred pygmy sunfish conservation

The bluebarred pygmy sunfish is considered a species of ‘Special Concern’ in South Carolina, while in Georgia it is listed as ‘Critically Imperiled’ (3). A species management plan has been proposed for the population in Georgia (3), and many of the South Carolina populations lie within the boundaries of private hunting clubs, where they benefit from indirect protection from development (3). A breeding programme for this species is currently underway at Riverbanks Zoo and Aquarium in South Carolina (8).

View information on this species at the UNEP World Conservation Monitoring Centre.
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Authentication

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:
arkive@wildscreen.org.uk

This species information was authored as part of the ARKive and Universities Scheme.
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Glossary

Anal fins
In fish, an unpaired fin on the under surface of a fish, behind the anus.
Caudal
The tail fin of a fish.
Dorsal fins
Relating to the back or top side of an animal.
Fertilisation
The fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.
Genus
A category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.
Invertebrates
Animals with no backbone.
Pectoral
In fish, the pair of fins that are found one on each side of the body just behind the gills. They are generally used for balancing and braking.
Pelvic fins
In fish, the pair of fins found on the underside of the body.
Spawning
The production or depositing of large quantities of eggs in water.
Territory
An area occupied and defended by an animal, a pair of animals or a colony.
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References

  1. IUCN Red List (March, 2010)
    http://www.iucnredlist.org
  2. Rohde, F.C. and Arndt, R.G. (1987) Two new species of pygmy sunfishes (Elassomatidae, Elassoma) from the Carolinas. Proceedings of the Academy of Natural Sciences of Philadelphia, 139: 65-85.
  3. Sandel, M. and Harris, P.M. (2007) Threatened fishes of the world: Elassoma okatie Rohde and Arndt 1987 (Elassomatidae). Environmental Biology of Fishes, 80: 487-488.
  4. Nelson, J.S. (1984). Fishes of the World. Second Edition. John Wiley and Sons, New York.
  5. Gilbert, C.R. (2004) Family Elassomatidae Jordan 1877 - pygmy sunfishes. California Academy of Sciences Annotated Checklists of Fishes, 33: 1-5.
  6. FishBase (January, 2010)
    http://www.fishbase.org
  7. Mettee, M.F. and Scharpf, C. (1998) Reproductive Behavior, Embryology, and Larval Development of Four Species of Pygmy Sunfish. American Currents, North American Native Fishes Association. Available at:
    http://www.nanfa.org/articles/elassoma.shtml
  8. Bettinger, J. (2005) Highest Conservation Priority - Coastal Plain Species. Department of Natural Resources, South Carolina.  Available at:
    http://www.dnr.sc.gov/cwcs/pdfhigh/HighestCoastalPlain.pdf
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Image credit

Male bluebarred pygmy sunfish  
Male bluebarred pygmy sunfish

© Tony Terceira

Tony Terceira
tony.terceira@gmail.com

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