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The Greenside Darter (Etheostoma blennioides) is a small, benthic freshwater fish belonging to the family Percidae. It is characterized by its elongated, somewhat compressed body, large pectoral fins, and distinctive green bars or blotches along its sides, particularly prominent in breeding males. This species is an important component of stream ecosystems, serving as both predator and prey, and is known for its unique reproductive behaviors.
Physical Characteristics
- Body shape
- elongated
- Coloration
- Overall olive to yellowish-brown dorsally, fading to a lighter ventral surface. The most striking feature is a series of 6-9 dark green, vertical bars or blotches along the sides, often connected by a lateral stripe. Breeding males exhibit vibrant emerald green on the sides, fins (especially the anal and pelvic fins), and sometimes the head. The first dorsal fin has a prominent orange or red band at its base, often bordered by a dark stripe, and a blue-green margin. The second dorsal and caudal fins are typically barred.
- Scale type
- ctenoid
- Mouth position
- subterminal
- Distinctive features
- Large, fan-like pectoral fins, Blunt snout with a subterminal mouth, Two dorsal fins, the first spiny and the second soft-rayed, Distinctive green vertical bars on sides (especially in males), Orange/red band at the base of the first dorsal fin
- Dorsal fin
- Two dorsal fins; the first with 10-13 spines, the second with 12-15 soft rays. The first dorsal fin is typically lower than the second.
- Tail fin
- Slightly emarginate to truncate caudal fin, often with vertical barring.
- Pectoral fin
- Large, fan-shaped pectoral fins with 13-15 rays, positioned low on the body.
- Distinctive fins
- Anal fin with 2 spines and 7-10 soft rays. Pelvic fins are thoracic, with 1 spine and 5 soft rays.
Identification Tips
Body Shape and Size
Look for an elongated, slender body, typically 7-12 cm (3-5 inches) in length. Maximum recorded length is around 15 cm (6 inches).
Coloration and Markings
The most reliable identifier is the series of 6-9 dark green vertical bars or blotches on the sides. Breeding males will have intense emerald green on their sides and fins, and a prominent orange/red band on the first dorsal fin.
Fins
Note the two distinct dorsal fins, with the first being spiny and the second soft-rayed. The large, fan-like pectoral fins are also characteristic.
Snout and Mouth
Observe the blunt snout and subterminal mouth, which is adapted for feeding on benthic invertebrates.
Habitat
If found in clear, cool, rocky riffles or runs with good current, it's likely a Greenside Darter.
Habitat
- Water type
- freshwater
- Depth
- Typically found in shallow to moderate depths (0.1-1.5 meters), but can be found deeper in larger rivers.
- Environment
- Prefers clear, cool to cold, moderate to fast-flowing riffles and runs of small to medium-sized rivers and larger creeks. They are typically found over gravel, cobble, or bedrock substrates, often associated with aquatic vegetation or filamentous algae. They avoid silty or heavily polluted waters.
- Geographic range
- Widely distributed in eastern North America, primarily in the Ohio River basin, Great Lakes basin (excluding Lake Superior), and parts of the Mississippi River basin. Its range extends from New York and Pennsylvania west to Wisconsin and Iowa, and south to northern Alabama and Georgia.
Aquarium Information
- Care level: intermediate
- Temperament: peaceful
- Diet: carnivore
- Minimum tank size: 20 gallons
- Temperature: 10-22°C (50-72°F)
- pH level: 6.5-7.5
- Hardness: 5-15 dGH
- Compatibility: Best kept with other small, peaceful, cool-water fish. Avoid aggressive or much larger species. Can be kept in groups of their own kind.
- Special requirements: Requires a well-oxygenated tank with strong current, plenty of hiding places (rocks, driftwood), and a substrate of sand or fine gravel. Sensitive to poor water quality. Live or frozen small invertebrates are essential for their diet.
Wild Information
- Conservation status: least concern
- Seasonality: Spawns primarily in spring (March-May), with activity peaking when water temperatures reach 10-18°C. Active year-round.
- Market price: N/A
- Commercial importance: none
- Taste: N/A
- Texture: N/A
- Nutritional value: N/A
Key Facts
Algae Scrapersbehavior
Greenside Darters are one of the few darter species known to actively graze on filamentous algae, using their blunt snout and subterminal mouth to scrape diatoms and other small organisms from the algal strands. This behavior is particularly common in juveniles and during certain times of the year.
Unique Spawning Behaviorbehavior
Unlike many darter species that bury their eggs, Greenside Darters are 'clump spawners.' Females deposit their eggs in thick masses of filamentous algae, often on the underside of rocks or logs, where they are then fertilized by the male. The male guards the nest for a period.
Indicator Speciesinteresting
Due to their preference for clear, well-oxygenated water and sensitivity to pollution and siltation, Greenside Darters are often considered an indicator species for good stream health and water quality.
Sexual Dimorphismbehavior
Greenside Darters exhibit strong sexual dimorphism, especially during the breeding season. Males develop much more vibrant green and orange coloration, enlarged fins, and sometimes tubercles (small bumps) on their fins, making them easily distinguishable from females.
Safety Information
Safe- Safety level: safe
- Venomous: No
- Edibility: not recommended
- Handling notes: Greenside Darters are harmless to humans. Handle gently if caught, as their scales can be easily damaged. Return to water quickly. No special precautions are needed.
Similar Species
Rainbow Darter
Etheostoma caeruleum
Rainbow Darters typically have more distinct, often reddish-orange and blue vertical bars, and generally lack the prominent green coloration of the Greenside Darter. Their snout is usually more pointed, and they tend to be smaller.
Fantail Darter
Etheostoma flabellare
Fantail Darters are generally smaller, have a more compressed body, and lack the distinct green bars. Males have fleshy knobs on the tips of the dorsal fin spines during breeding season, which are absent in Greenside Darters. Their caudal fin is often rounded.
Johnny Darter
Etheostoma nigrum
Johnny Darters have a series of 'W' or 'X' shaped markings along their sides, rather than vertical bars. They are typically found in slower-moving water and often have a more mottled brown coloration.
Scientific Classification
- Kingdom
- Animalia
- Phylum
- Chordata
- Class
- Actinopterygii
- Order
- Perciformes
- Family
- Percidae
- Genus
- Etheostoma
- Species
- blennioides
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