Sternopygus

Sternopygus is a genus of knifefish in the family Sternopygidae, commonly known as glass knifefish. These fish are native to South America and are found in a variety of freshwater habitats, including rivers, streams, and lakes. They are characterized by their elongated, eel-like bodies, which are often transparent or semi-transparent, giving them their common name.

The most striking feature of Sternopygus is their pectoral fins, which are small and paddle-like, and their dorsal and anal fins, which are greatly elongated and undulate to provide propulsion. They also possess a small caudal fin. Their mouths are typically small and upturned, adapted for feeding on small invertebrates and insect larvae.

Species within the Sternopygus genus are known for their use of electrolocation and electrogeneration. They possess a weakly electric organ that they use to navigate, communicate, and detect prey in their often murky environments. This electric field is also used in social interactions and for species recognition.

Reproduction in Sternopygus typically involves the female laying eggs, which are then fertilized by the male. The number of eggs and the parental care, if any, can vary between species. They are generally peaceful fish and are often kept in aquariums by hobbyists who appreciate their unique appearance and behavior.