How to Identify Threadfin Acara

To identify Threadfin Acara (Acarichthys heckelii), look at these key features.

Physical Characteristics

Body shape

compressed

Coloration

Base coloration is typically silvery-grey to light brown, often with iridescent scales. A prominent dark spot is usually present on the flank, sometimes surrounded by a lighter halo. Fins can have a yellowish or reddish tint, especially the caudal fin. Males often display more intense coloration and longer fin extensions.

Scale type

ctenoid

Mouth position

terminal

Distinctive features

Elongated, filamentous rays on the dorsal and anal fins, particularly pronounced in adult males., A distinct dark spot on the mid-flank., Substrate-sifting mouth and gill rakers adapted for feeding on benthic invertebrates.

Dorsal fin

Long and continuous, extending from behind the head almost to the caudal fin, with the posterior soft-rayed portion having elongated, thread-like extensions.

Tail fin

Lunate to slightly emarginate, often with reddish or yellowish hues.

Pectoral fin

Transparent to slightly yellowish, typically rounded.

Distinctive fins

Pelvic fins are often elongated, especially in males, and can be used in display.

Identification Tips

1. 1

   Fin Extensions

   Look for the characteristic long, filamentous extensions on the dorsal and anal fins, which are most prominent in adult males. This is the primary distinguishing feature.

2. 2

   Lateral Spot

   Observe the distinct dark spot located on the mid-flank of the body. This spot can vary in intensity and may be surrounded by a lighter area.

3. 3

   Body Shape and Coloration

   Note the compressed, somewhat oval body shape and the silvery-grey to light brown base color, often with iridescent scales. Fin coloration can also be a clue.

4. 4

   Behavior

   Their characteristic substrate-sifting behavior, where they take mouthfuls of sand and expel it through their gills, is a strong indicator.

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