Characiforms

Characiforms are a diverse order of freshwater fish that includes familiar species like tetras, piranhas, and pacus. They are characterized by the presence of an adipose fin, a small fleshy fin located behind the dorsal fin. This fin is typically small and may be absent in some species, but its presence is a key diagnostic feature of the order. Characiforms are found in freshwater habitats across South America, Africa, and parts of Asia.

Their diet varies greatly depending on the species. Some characiforms are herbivorous, feeding on plants and fruits, while others are carnivorous, preying on insects, smaller fish, and other invertebrates. The iconic piranhas, for example, are known for their sharp teeth and carnivorous habits. Pacus, on the other hand, have flatter teeth adapted for crushing seeds and fruits.

Characiforms exhibit a wide range of body shapes and sizes, from the tiny, schooling tetras to the larger, more robust pacus. Many species are popular in the aquarium trade due to their vibrant colors and interesting behaviors. Their evolutionary history is complex, and they are thought to have originated in South America. The order is divided into several families, each with unique adaptations to their specific environments. They play important roles in their ecosystems, serving as both prey and predators.