The Clown Knifefish (Chitala ornata), known locally as මන්නයා (Mannaya), is an introduced freshwater species in Sri Lanka belonging to the family Notopteridae. Native to the river basins of Southeast Asia, it was introduced to Sri Lanka primarily through the ornamental aquarium trade, with accidental escapes and deliberate releases leading to established populations in several lowland rivers, marshes, and reservoirs.

It is easily distinguished by its strongly compressed, blade-like body structure, a long continuous anal fin that joins the caudal fin, and a row of dark, ringed spots (ocelli) running along the lower rear portion of its body. As a nocturnal, predatory species, it uses its flexible locomotion and keen senses to navigate murky waters, feeding primarily on smaller native fishes, crustaceans, and aquatic insects. Due to its large adult size, predatory nature, and rapid growth, it poses a notable ecological threat to indigenous freshwater fish populations across Sri Lanka's aquatic ecosystems.