Cardinal Tetras (Paracheirodon axelrodi) are vibrant, peaceful fish that bring a splash of color to any freshwater aquarium. Originating from the Amazon rainforest, these schooling fish have become a favorite among both beginner and experienced aquarists. This guide provides comprehensive information on their diet, care, and habitat to help you create a thriving environment for your Cardinal Tetras.
Introduction to Cardinal Tetras
Cardinal Tetras are known for their bright red and blue coloration, similar to Neon Tetras, but with the red extending the full length of their body. These small fish typically grow to about 1.5 inches in length. They are peaceful and thrive in groups, making them an excellent choice for community aquariums.
Natural Habitat
Cardinal Tetras are native to the Amazon River basin in South America, specifically in areas of Brazil, Colombia, and Venezuela. They inhabit slow-moving, shallow streams and swampy river side arms with dark, stained water and plenty of vegetation. The water in their natural habitat is typically acidic and soft, with a pH ranging from 4 to 6 and a water hardness of less than 4 dKH. The streams are small and shallow, generally under 2ft deep, with not too much direct sun and a thick layer of leaf litter on the bottom. There tends to be plenty of vegetation around the edges, particularly palm trees. The natural palm swamp habitat of this fish is characterized by seasonal fluctuations. During the dry season, shoals can end up in small pools in areas that maintain some water year-round.
Aquarium Setup
Tank Size
To provide enough space for Cardinal Tetras to swim and school, it is recommended to house them in a tank that is at least 20 gallons. A long tank is preferable to a high tank, as they prefer shallow water.
Water Parameters
Maintaining optimal water parameters is crucial for the health and well-being of Cardinal Tetras. Aim for the following:
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- pH: 5.0 to 7.0
- Temperature: 74°F to 82°F (23°C to 28°C)
- General Hardness (GH): 1 to 8 dGH
- Carbonate Hardness (KH): 1 to 4 dKH
- Conductivity: Between 100 and 400 µS/cm
Regularly test the water using reliable testing kits and make gradual adjustments as needed to avoid stressing the fish.
Substrate and Decorations
Dark substrates and decorations will help accent the bright colors of your tetras. Recreating their natural habitat as best as you can is a good idea. The Rio Negro is a blackwater river whose side arms are full of leaf litter and plant roots. Your cardinal tetras will appreciate something similar in the aquarium: dark water (stained using a layer of leaves on the bottom), relatively dim lighting, and plenty of wood and leaves scattered about.
Lighting and Filtration
Cardinal Tetras thrive in dimly lit environments with subdued lighting, mimicking their natural habitat. A reliable filtration system is necessary to maintain optimal water quality. Choose a filter that provides efficient mechanical and biological filtration.
Cardinal Tetra Diet
Understanding the natural feeding habits of Cardinal Tetras is crucial for their overall health and well-being. They are omnivores and micropredators, primarily feeding on microcrustaceans like daphnia and copepods in the wild.
Recommended Foods
- High-Quality Flakes or Pellets: Select foods specifically formulated for tropical fish, containing a mix of animal and plant-based ingredients. Tetra Prima is a popular option, but be aware that it sinks quickly.
- Micro Granules: Fluval Bug Bites do a micro granule that sinks slow.
- Live or Frozen Foods: Supplement their diet with live or frozen foods such as daphnia, bloodworms, and brine shrimp for enrichment.
- Floating Micropellets: High-quality floating micropellets for carnivores can be offered.
Feeding Schedule and Techniques
- Small Portions: Feed small portions multiple times a day, as Cardinal Tetras have small stomachs.
- Two-Minute Rule: Offer only what they can consume in under 2 minutes to avoid overfeeding.
- Variety: Rotate between flakes or pellets and live or frozen foods throughout the week for a varied and balanced diet.
- Feeding Ring: Using a feeding ring can help prevent flake food from sinking too quickly.
- Stick on Tabs: Stick on Tabs are great for target feeding, as you can watch the fish eating the food infront of you over an hr or so.
Food Options and Considerations
- Tetra Prima: While a popular choice, its rapid sinking may not be ideal. Crispa can be crumbled up for easier feeding.
- NTLabs Pellets: These pellets, including a crumb that floats for a while before sinking, are a good alternative.
- Sinking Foods: For tanks with fish that occupy the mid to bottom levels, like Glowlights, add sinking foods a bit at a time during feeding sessions.
Tank Mates
Most tetras are peaceful and get along well with similarly sized community fish, but there are a few exceptions. Serpae tetras, for example, can sometimes be nippy, especially when kept in insufficient numbers. Others, like Buenos Aires tetras get quite large and are very active, which may intimidate smaller, more timid fish. Good tank mates for tetras include other tetra species, rasboras, small danios, peaceful barbs, appropriately sized rainbowfish and livebearers. Always consult an aquarium expert before buying any new fish for your aquarium.
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Suitable Tank Mates
Cardinal Tetras are peaceful fish and do well with other non-aggressive species. Good tank mates include:
- Other Tetra Species
- Rasboras
- Small Danios
- Peaceful Barbs
- Appropriately Sized Rainbowfish
- Livebearers
- Dwarf Shrimp (with caution, as Cardinal Tetras may eat baby shrimp)
Tank Mates to Avoid
Avoid keeping Cardinal Tetras with aggressive or fin-nipping fish, as they may harass the tetras. Examples include:
- Serpae Tetras (can be nippy)
- Buenos Aires Tetras (large and active)
- Betta Fish (may be targeted due to their long fins)
Behavior and Compatibility
Cardinal Tetras are schooling fish and should be kept in groups of at least 10 to feel secure. They are generally peaceful and non-aggressive, making them suitable for community aquariums.
Breeding Cardinal Tetras
Breeding Cardinal Tetras in captivity can be challenging but rewarding.
Setting Up a Breeding Tank
- Separate Tank: Set up a separate breeding tank to protect the eggs and fry from the adults.
- Water Parameters: Maintain slightly acidic water with a pH range of 5.0 to 7.0 and a temperature between 78°F to 82°F (25°C to 28°C).
- Vegetation and Lighting: Add dense vegetation and dim lighting to simulate their natural breeding environment.
Spawning and Fry Care
- Introduce Tetras: Introduce a group of male and female Cardinal Tetras into the breeding tank.
- Egg Scattering: The fish will engage in a courtship display and scatter their eggs into the water column.
- Remove Adults: After spawning, remove the adults to prevent them from eating the eggs or fry.
- Feed the Fry: Feed the fry infusoria, small live foods, or commercially available fry food.
- Maintain Water Quality: Perform regular water changes and monitor water parameters to ensure the survival and growth of the fry.
Common Issues and Solutions
- Disease Prevention: Maintain high water quality and quarantine new fish before introducing them to the main tank to prevent the spread of disease.
- Stress Reduction: Provide plenty of hiding places and keep them in a school to reduce stress.
- Fin Nipping: Ensure they are kept in a large enough group to prevent fin nipping.
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