The Cardinal Tetra, scientifically known as Paracheirodon axelrodi, is a small and vibrant freshwater fish native to the Amazon River basin in South America. These fish have a slender and elongated body shape with a distinctive iridescent blue-green upper body and a vibrant red lower body. They display a horizontal blue or turquoise stripe that extends from the middle of their body to the base of their tail. Their fins are transparent with a hint of red in the dorsal fin.

Cardinal Tetras are peaceful shoaling fish, and they prefer to live in groups of their own kind. They feel more secure and display their best colors when kept in groups of at least six or more. They are relatively active swimmers and spend their time exploring the middle and lower regions of the aquarium. Their shoaling behavior adds a lively and captivating element to the aquarium.

In their natural habitat, Cardinal Tetras inhabit slow-moving and shaded tributaries of the Amazon River. These water bodies are often characterized by dense vegetation, fallen branches, and leaf litter. When setting up an aquarium for Cardinal Tetras, it is essential to replicate their natural environment by providing plenty of plants, dim lighting, and soft, slightly acidic water.

Caring for Cardinal Tetras requires attention to water quality and suitable tank conditions. They thrive in aquariums with a temperature range suitable for tropical fish and water that is slightly acidic to neutral in pH. Good filtration and regular water changes are important to maintain optimal water quality.

Cardinal Tetras are omnivorous and readily accept a variety of foods. Their diet can include high-quality flake or pellet foods, as well as live or frozen foods such as bloodworms, brine shrimp, and daphnia. Offering a varied diet will help ensure their nutritional needs are met.

When it comes to tank mates, Cardinal Tetras are generally peaceful and can coexist with other small, peaceful fish that share similar water requirements. Suitable tank mates can include other peaceful tetra species, rasboras, small catfish, and peaceful dwarf cichlids. It's important to avoid keeping them with larger or aggressive fish that may intimidate or harass them.

Breeding Cardinal Tetras in captivity can be challenging, as they require specific conditions and stimuli to initiate spawning. Providing a suitable spawning site, such as fine-leaved plants or a spawning mop, can encourage breeding behavior. The eggs are adhesive and will stick to the spawning substrate. The parents do not exhibit parental care, so it's essential to remove the eggs or fry to a separate rearing tank to protect them from being eaten by the adults.

In conclusion, Cardinal Tetras are beautiful and peaceful shoaling fish that can add vibrant colors and activity to the aquarium. With proper care and suitable tank conditions, they can thrive and provide a captivating display for any aquarist.