The Family Characinidae is commonly known as the characids or characins, which are a diverse group of freshwater fish found in South America and Africa. Some synonyms for this family of fish include tetras, piranhas, hatchetfish, and pencilfish. Tetras are small and colorful, commonly found in aquariums. Piranhas, on the other hand, have a fierce reputation as carnivores, known for their razor-sharp teeth. Hatchetfish have a unique shape with an elongated body and a short, hatchet-shaped head. Pencilfish have a slim and elongated body with a pointed snout. The Family Characinidae is a fascinating group of fish with plenty of variety to suit any aquarist's preference and interest.