Splash Tetra

The splash tetra (Copella arnoldi) is a small, slender characin from slow-moving forest streams of the lower Amazon and Guyana in South America. It is best known for one of the most remarkable reproductive strategies in fishes: mated pairs leap together out of the water to attach eggs to leaves or other surfaces overhanging the stream, safely out of reach of aquatic predators. Males then repeatedly splash water onto the eggs with their tail to keep them moist until hatching, after which the fry drop into the water below. This unusual out-of-water spawning behavior has made the species a long-standing favorite among aquarium hobbyists interested in unusual fish behavior, alongside its attractive iridescent coloration and elegant fins.

• Slender, elongated body with an olive to golden iridescent sheen
• Dark horizontal stripe running from snout through the eye to the tail
• Males have an enlarged, fan-shaped upper caudal fin lobe, often reddish-black with white edging
• Females are smaller with plainer, less extended fins
• Look-alikes: other Copella and Corynopoma species share slim shapes but lack the extreme male tail-fin elaboration and leaping spawning behavior

Splash tetras inhabit shaded, slow-flowing forest streams, blackwater creeks, and flooded margins of the lower Amazon basin and coastal Guyana in South America. They favor soft, acidic, tannin-stained water beneath dense forest canopy, often near overhanging vegetation, roots, or leaves that hang just above the water surface, which are essential for their unusual spawning behavior. Water in these habitats is typically warm, low in dissolved minerals, and low in oxygen relative to open rivers, conditions the species is well adapted to tolerate. They are usually found near the surface in quiet backwaters rather than in strong current.

Splash tetras are best known for their extraordinary spawning ritual: a courting pair repeatedly leaps together out of the water, briefly clinging to the underside of an overhanging leaf with fins, where the female deposits a row of adhesive eggs fertilized by the male before both fish fall back into the water. The male then remains below, periodically splashing water upward with his tail every few minutes to keep the exposed eggs moist until they hatch, typically within two to three days, after which fry drop directly into the water. This behavior protects eggs from aquatic egg predators. Outside of spawning, splash tetras feed near the surface on small insects, larvae, and other invertebrates, often taking prey that fall onto the water.