When young, these fish display a mottled appearance with irregular black patches, which intensify in darkness as they mature. Adult specimens take on a dark brownish olive hue on their backs, gradually lightening towards white on their ventral surfaces. Notably, they bear a distinct black, vertical blotch situated in the middle of their bodies, just above the origin of the pelvic fin. Additionally, a second black, vertical blotch is located above the anal fin, and a third black bar or blotch can be observed at the base of the caudal fin, although it is somewhat less defined compared to the other two. Their fins are characterized by their thin and translucent nature.
Distinguishing between genders, the dorsal fins are longer in males, while females possess shorter dorsal fins that are more fully edged. Males typically exhibit a noticeable physical change during their spawning condition, marked by eruptions around the mouth in the form of small white spots. In contrast, females tend to have a rounder physique. It's important to note that the Arulius barb attains its full coloration later in life, often leading to it being overlooked.
As is common with many barbs, these fish may exhibit nippy behavior, which can be mitigated by maintaining them in groups of at least 5 to 6 individuals within the aquarium. It's essential to consider the space requirements, as these fish can reach an adult size of 4 to 5 inches (10-12 cm).
For successful breeding, it is recommended to utilize a spacious tank equipped with thickets of fine-leaved plants. Breeding is preceded by an energetic swimming ritual, followed by spawning near the water's surface. These fish will lay adhesive eggs on any available plants in the breeding tank, usually numbering fewer than 100. Similar to most barbs, it is crucial to remove the parents after spawning to prevent them from consuming the eggs. After 24-48 hours, the eggs will hatch, and once the fry become free-swimming, they should be provided with Infusoria as their initial food source, transitioning to newly hatched brine shrimp as they develop.