Tetra

Cardinal Tetra

Cardinal tetras are mesmerizing freshwater fish closely related to Neon Tetras. With their striking red and blue colors, they have become a favorite among aquarium enthusiasts. These friendly fish require minimal maintenance, making them an excellent choice for community aquariums.

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Care DIfficulty

Beginner-Friendly

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Temperament

Peaceful

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Origin

South America

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Size

1.5 inches (3.8 cm)

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Lifespan

4 to 5 years

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Table of contents

Origin, Appearance, Size, and Lifespan

The Cardinal Tetra, or Paracheirodon axelrodi, often referred to as the Red Neon Tetra, is a popular freshwater fish hailing from the Amazon River basin in South America. You'll usually find them in the tributaries of the Rio Negro, which flows through Brazil, Colombia, and Venezuela.

In the wild, Cardinal Tetras are most often found in calm, shallow waters with an abundance of plant life. These plants not only serve as hiding spots but also as a food source, while the dark riverbeds make their vibrant colors stand out. These social fish thrive in groups of at least six, but it's not uncommon to see them in schools of 20 to 30 or more.

Their natural environment features warm, soft, and acidic water. The temperature typically varies between 73 to 82 degrees Fahrenheit (23 to 28 degrees Celsius), with a pH level of 4.0 to 6.5, and water hardness between 1 to 2 dGH. To create a similar environment in your aquarium, make sure to maintain a consistent water temperature, use a top-quality filtration system, and incorporate live plants and driftwood.

By closely mirroring the Cardinal Tetra's natural habitat and ensuring the right water conditions, you'll be setting your fish up for a healthy and happy life in your aquarium.

Cardinal Tetras are celebrated for their striking neon blue stripe that adorns their bodies, complemented by a vivid red stripe on the lower half. These brilliant colors make them an irresistible and eye-catching feature in aquariums. Even though they are small, reaching up to approximately 1.5 inches (3.8 cm) in size, their distinctive hues and animated nature make them an ideal choice for those seeking a dynamic, vibrant aquatic showcase. These charming fish bring joy to observers as they swiftly glide through the tank, making them a cherished favorite among hobbyists of all experience levels.

With proper care, Cardinal Tetras can enjoy a lifespan of up to five years. As sociable beings, they flourish in groups and are best kept in schools of a minimum of six individuals. To promote their well-being and ensure a long life in captivity, it's essential to provide a lushly planted aquarium with abundant hiding spots, as well as a diverse diet consisting of premium flakes, pellets, and frozen foods.

Fun Facts

Now that learned more about the appearance and lifespan of Cardinal Tetras. In this section, we'll highlight some fascinating facts about these beautiful fish that make them stand out in the aquarium hobby. From their striking coloration to their social behavior, Cardinal Tetras are full of surprises and are sure to captivate any aquarist.

  • Mimicry for survival: In the wild, Cardinal Tetras are often found swimming with Neon Tetras, which share a similar appearance. This mimicry helps both species increase their numbers and confuse predators, increasing their chances of survival.
  • Natural sunscreen: Cardinal Tetras have a unique pigment called erythrophore, which helps them survive in the dark, tannin-stained waters of their natural habitat. This pigment acts as a natural sunscreen, protecting the fish from harmful ultraviolet (UV) radiation that penetrates the water surface.
  • Glassfish relative: Despite their colorful appearance, Cardinal Tetras are closely related to glassfish (family Characidae), which are known for their transparent bodies. Cardinal Tetras, however, have developed bright colors as a form of camouflage and communication in their dimly lit habitats.
  • Ability to change colors: Cardinal Tetras can change the intensity of their colors based on their surroundings, mood, or health. In dimly lit conditions or when stressed, their colors may appear less vibrant. Conversely, when they feel secure and healthy, their colors become more vivid, making them stand out in an aquarium setting.
  • Shoaling behavior: Cardinal Tetras are shoaling fish, meaning they prefer to swim together in groups. This behavior not only helps them feel secure but also creates a stunning visual display in an aquarium. Their coordinated movements and dazzling colors can transform a home aquarium into a mesmerizing underwater scene.

Now that you've discovered some interesting tidbits about Cardinal Tetras, you'll be better equipped to appreciate their beauty and intricacies in your aquarium. In the following section, we'll provide recommendations on tank setups, ensuring your Cardinal Tetras have an ideal environment to thrive and showcase their dazzling features.

Recommended Tank Setups

Each setup includes the core components—tank, filter, heater, lighting, substrate, and more—ensuring that you can create an appropriate environment for Cardinal Tetras and other compatible freshwater fish species in your aquarium. As you move from budget-friendly to high-end setups, you will also have more options for customization, aesthetics, and advanced features. Cardinal Tetras are schooling fish and need to be kept in groups of at least six individuals to reduce stress and ensure their well-being. Typically, Cardinal Tetras are priced between $2 and $4 per fish, although prices can vary based on factors such as size, quality, and availability.


Budget-friendly setup (around $200):‍

  • Tank: 20-gallon aquarium with a hood or glass canopy‍ ($40 - $70)
  • Filter: Hang-on-back (HOB) or sponge filter rated for 20 gallons ($20 - $40)
  • Heater: 50-100 watt adjustable aquarium heater ($15 - $30)
  • Lighting: Basic LED aquarium light ($20 - $50)
  • Substrate: Inexpensive aquarium sand or small gravel ($10 - $20)
  • Decor: A few pieces of driftwood and rocks, along with low-cost live plants like Java Fern and Anubias ($20 - $40)
  • Fish: Minimum 6, maximum 10 Cardinal Tetras ($20 - $30)
  • Thermometer: $3 - $10
  • Substrate Vacuum: $10 - $25
  • Fish Net: $2 - $10
  • Algae Scraper or Magnetic Cleaner: $5 - $20
  • Siphon and Bucket: $15 - $30
  • Test Kit: $15 - $50
  • Fish Food: $5 - $20
  • Water Conditioner: $5 - $15

Mid-range setup (around $400 - $650):‍

  • Tank: 20-30 gallon aquarium with a hood or glass canopy ($60 - $120)
  • Filter: Canister filter or high-quality HOB filter rated for the tank size ($60 - $150)
  • Heater: 100-150 watt adjustable aquarium heater ($25 - $50)
  • Lighting: LED aquarium light with adjustable settings for plant growth and color enhancement ($50 - $150)
  • Substrate: Nutrient-rich aquarium substrate designed for planted tanks ($20 - $40)
  • Decor: A mix of driftwood, rocks, and live plants such as Amazon Swords, Java Fern, Anubias, and Cryptocoryne species ($40 - $80)
  • Fish: Minimum 6, maximum 15 Cardinal Tetras ($20 - $50)
  • Thermometer: $3 - $10
  • Substrate Vacuum: $10 - $25
  • Fish Net: $2 - $10
  • Algae Scraper or Magnetic Cleaner: $5 - $20
  • Siphon and Bucket: $15 - $30
  • Test Kit: $15 - $50
  • Fish Food: $5 - $20
  • Water Conditioner: $5 - $15

High-end setup (above $800):‍

  • Tank: 30-40 gallon rimless aquarium with a glass canopy ($120 - $250)
  • Filter: High-quality canister filter rated for the tank size ($100 - $250)
  • Heater: 150-200 watt adjustable aquarium heater with an external temperature controller ($40 - $80)
  • Lighting: Advanced LED lighting system with customizable settings for plant growth, color enhancement, and day/night cycles ($150 - $300)
  • Substrate: Premium aquarium substrate designed for planted tanks, with added root tabs for extra plant nutrition ($30 - $60)
  • Decor: A combination of driftwood, rocks, and live plants to create a natural aquascape, featuring plant species such as Amazon Swords, Java Fern, Anubias, Cryptocoryne species, and carpeting plants like Dwarf Hairgrass or Monte Carlo ($60 - $150)
  • Fish: Minimum 6, maximum 20 Cardinal Tetras ($20 - $70)
  • Thermometer: $3 - $10
  • Substrate Vacuum: $10 - $25
  • Fish Net: $2 - $10
  • Algae Scraper or Magnetic Cleaner: $5 - $20
  • Siphon and Bucket: $15 - $30
  • Test Kit: $15 - $50
  • Fish Food: $5 - $20
  • Water Conditioner: $5 - $15

Please note that these numbers are just recommendations, and you should consider other factors such as tank mates and individual fish personalities when deciding how many Cardinal Tetras to keep in your aquarium. Prices may vary depending on location, brand, and availability.

Set Up Your Tank

In the previous section, we discussed the recommended tank setups for your Cardinal Tetras and other fish. Now that you have a better understanding of what's required, let's dive into the step-by-step process of setting up your aquarium. These steps will guide you through selecting the ideal location for your tank, cleaning and preparing the tank, installing essential equipment, and cycling the water to create a healthy environment for your fish. We'll also cover the proper acclimation process to ensure a smooth transition for your Cardinal Tetras and other fish into their new home. By following these guidelines, you'll be well on your way to creating a thriving aquatic ecosystem for your fish to flourish in.

  • Step #1: Choose the perfect spot for your aquarium, making sure it's away from direct sunlight, heat sources, and drafts. Ensure the surface is level and sturdy enough to support your filled tank. If your aquarium requires a stand, assemble it according to the manufacturer's instructions and place the empty tank on it.
  • Step #2: Next, clean the tank by rinsing it with clean water (avoid using soap or chemicals) to remove dust or debris. Wipe the inside with a clean cloth or paper towel. Rinse the substrate (sand or gravel) thoroughly in a bucket until the water runs clear, then spread it evenly across the bottom of the tank, creating a slight slope towards the back for visual depth.
  • Step #3: Before filling the tank with water, plan the layout of your aquarium, including the position of equipment like heaters and filters. This will make it easier to set up and maintain the tank in the long run. Install the heater and filter according to the manufacturer's instructions. If you're using a sponge or under-gravel filter, place it beneath the substrate before adding water.
  • Step #4: Decorate the tank with driftwood, rocks, and plants to create hiding spots and a visually appealing environment, ensuring there are open swimming areas for your fish. When decorating the tank, be careful to arrange driftwood, rocks, and plants in a way that won't damage or obstruct the equipment. You can also anchor plants to driftwood or rocks to help them stay in place.
  • Step #5: Fill the tank with water treated with a water conditioner if your tap water contains chlorine or chloramines. Place a clean plate or plastic bag on the substrate to prevent disturbance while filling. Fill the tank until it's about 2/3 full. Attach the aquarium light to the hood or canopy, following the manufacturer's instructions. Consider using a timer for your aquarium light to maintain a consistent day and night cycle, which is essential for fish and plants. Connect the heater, filter, and any additional equipment (air pump, CO2 system) to power sources, and install the thermometer in an easily visible location.
  • Step #6: Top off the water, leaving space between the water surface and the top of the tank for oxygen exchange. Turn on the filter, heater, and other equipment. Monitor the water temperature and adjust the heater as needed. Allow the tank to cycle for 4-6 weeks to establish beneficial bacteria and stabilize water parameters. During the cycling process, you can add a bacterial starter culture to speed up the establishment of beneficial bacteria in the tank. Use an aquarium test kit to monitor ammonia, nitrite, and nitrate levels.
  • Step #7: After the tank has cycled and water parameters are stable, slowly acclimate your Cardinal Tetras and other fish to the tank's conditions before introducing them. Begin by floating the unopened fish bag in the tank for 15-20 minutes to equalize the temperature. Afterward, open the bag and add a small amount of tank water to it. Continue adding small amounts of tank water to the bag every 5-10 minutes for at least 30-60 minutes, allowing the fish to adjust to the new water chemistry gradually. Use a net to gently transfer the fish from the bag to the tank, avoiding any unnecessary stress or exposure to the water from the bag.
  • Step #8: Once all the fish are introduced, establish a consistent daily feeding schedule, providing high-quality food in appropriate amounts for your fish species. Perform regular water changes (20-30% every 1-2 weeks) and monitor water parameters using a test kit to maintain a healthy environment for your fish. Observe your fish closely for any signs of stress or illness, especially during the first few weeks after introduction. Be prepared to take action if necessary, such as adjusting water parameters or seeking advice from an experienced aquarist.

By following this step-by-step guide and incorporating the additional setup tips, you can create a thriving aquatic environment that will help your Cardinal Tetras and other fish flourish in their new home.

Recommended Water Parameters

To keep your Cardinal Tetras healthy and happy, it's important to maintain specific water parameters in your aquarium. Here's a breakdown of what to aim for:

  • Temperature: Keep the water between 73°F and 81°F (23°C and 27°C) for optimal comfort.
  • pH: Aim for a slightly acidic pH of 5.5 to 7.0, but they can tolerate up to 7.5 if changes are gradual.
  • Hardness: Soft to moderately hard water (1-10 dGH) is ideal, though they can adapt to slightly harder water.
  • Ammonia, Nitrite, and Nitrate: Keep ammonia and nitrite at 0 ppm, and maintain nitrate levels below 20 ppm.
  • Lighting: Provide low to moderate lighting with shaded areas and plants to prevent stress.
  • Water movement: Moderate water flow is best, mimicking their natural slow-moving habitat.

Make sure to test your aquarium water regularly and perform necessary water changes to keep the environment stable.

Routine Water Maintenance

Water changes are crucial for a healthy Cardinal Tetra tank. They help remove excess nutrients, waste, and toxins. Here's a suggested routine:

  • Weekly water changes: Replace 20-25% of the tank water every week.
  • Test water parameters: Check pH, ammonia, nitrite, nitrate, and hardness regularly.
  • Use a gravel vacuum: Clean the substrate during water changes.
  • Dechlorinate the water: Treat tap water with a water conditioner before adding to the aquarium.
  • Match temperature and pH: Ensure new water is similar to the tank water.
  • Acclimate the fish: Give your fish time to adjust to new conditions after water changes.

In addition to routine water maintenance, consider the following to ensure the health of your fish and the overall appearance of your aquarium:

  • Monitor lighting duration: Keep track of how long your aquarium lights are on each day, aiming for a consistent 8-10 hour photoperiod. Too much light can lead to excessive algae growth.
  • Plant maintenance: Regularly trim live plants to maintain their health and appearance. Remove any dead leaves or plant matter to prevent water quality issues.
  • Filter maintenance: Clean or replace the filter media as recommended by the manufacturer, usually every 4-6 weeks. Avoid replacing all filter media at once, as this can disrupt the beneficial bacteria and lead to water quality issues.‍

Diet and Feeding Schedule

Cardinal Tetras are omnivores and require a diverse diet. Here are some feeding guidelines:

  • Flakes and pellets: Use high-quality flake or pellet food designed for small tropical fish.
  • Frozen and live foods: Offer brine shrimp, bloodworms, daphnia, or mosquito larvae as occasional treats.
  • Vegetable matter: Provide blanched spinach, zucchini, or cucumber for added nutrients.
  • Feeding frequency: Feed modest portions two to three times a day, and avoid overfeeding.

Stress and Diseases

Cardinal tetras may experience stress from various sources, such as poor water quality, aggression, or unsuitable tank conditions. Identifying and addressing these stressors is vital for your fish's health and well-being:

  • Watch for stress signs: Keep an eye on your Cardinal tetras for unusual behavior like hiding, lethargy, color loss, or rapid breathing, which may indicate stress.
  • Check water quality: Test your aquarium water to ensure it meets the ideal parameters and conduct regular water changes to maintain a healthy environment.
  • Monitor tank mates: Make sure your Cardinal tetras aren't being harassed or attacked by other fish and remove any aggressive tank mates if needed.
  • Create a suitable habitat: Provide plenty of hiding spots, appropriate lighting, and a properly sized tank for your fish.

While Cardinal tetras are generally hardy, they can be susceptible to some common fish diseases, such as:

  • Ich (white spot disease): A prevalent parasitic infection causing white spots on the body and fins, lethargy, and appetite loss. Treat Ich with aquarium salt or anti-parasitic medication and raise the water temperature to around 82°F (28°C).
  • Fin rot: A bacterial infection that leads to frayed or discolored fins and tail. Treat fin rot with a partial water change, aquarium salt, and antibacterial medication containing erythromycin or tetracycline.
  • Velvet disease: A parasitic infection causing a yellow or brownish velvet-like coating on the fish's body. Treat velvet disease with anti-parasitic medication containing copper sulfate or formalin.
  • Swim bladder disease: A condition where fish have difficulty swimming upright. Treat swim bladder disease by fasting the fish and offering them blanched peas, and consider using an antibacterial medication if needed.

Prevent diseases in Cardinal tetras by maintaining excellent water quality, avoiding overfeeding, and providing a balanced diet. Quarantine new fish before adding them to the main tank and promptly address any signs of illness.

Breeding

Breeding Cardinal Tetras can be a challenging undertaking, but it is achievable with the right setup and conditions. Follow these steps to breed Cardinal Tetras:

  • Step #1: Create a suitable breeding environment with a separate 10-gallon or larger breeding tank, a pH level of around 6.0 to 6.5, and a temperature of about 80°F (27°C). Maintain soft water (1-4 dGH) and include hiding spots like plants and spawning mops for the fish's comfort.
  • Step #2: Select healthy, mature male and female Cardinal Tetras for breeding. Maintain a ratio of two females to one male to prevent aggression and rivalry. You can determine the gender by observing their physical characteristics and behavior.
  • Step #3: Prepare the breeding pair with a high-protein diet of live or frozen foods for several weeks to help them build strength and energy.
  • Step #4: Encourage spawning by introducing the pair to the breeding tank, gradually raising the water temperature, and dimming the lighting. Simulate a natural day-night cycle by gradually increasing and decreasing the lighting duration in the breeding tank. Include a spawning mop or fine-leaved plants for egg depositing.
  • Step #5: Care for the eggs and fry by removing the breeding pair after spawning. Keep the breeding tank in a dimly lit area, as the eggs and fry are sensitive to light. Eggs will hatch within 24-36 hours, and the fry will become free-swimming after several days. Gradually increase the lighting duration as the fry grow. Feed them infusoria or liquid fry food initially, then gradually introduce crushed flake food.
  • Step #6: Monitor the growth and development of the fry, and separate them by size if needed to prevent larger fry from preying on smaller ones.

Breeding Cardinal Tetras can be a rewarding experience for experienced hobbyists. Patience and the right conditions are key to success.

Recommended Tank Mates

Here are the top 10 recommended tank mates for Cardinal Tetras:

  1. Dwarf Corydoras
  2. Neon Tetras
  3. Ember Tetras
  4. Guppies
  5. Bristlenose Plecos
  6. Pygmy Corydoras
  7. Cherry Shrimp
  8. Nerite Snails
  9. Rasboras
  10. Otocinclus Catfish

Remember to avoid large, aggressive fish like cichlids, angelfish, and predatory species, as they may harm or eat the Cardinal Tetras. Always observe the behavior of new fish and ensure they don't cause stress or aggression towards the Cardinal Tetras.

Conclusion

To summarize, Cardinal tetras are a captivating species of freshwater fish renowned for their striking colors and ease of care. These fish necessitate specific water parameters, a well-balanced diet, and a suitable environment to thrive in captivity. However, with the right conditions, they can live up to five years and be an excellent addition to any aquarium. When selecting tank mates, it's crucial to choose peaceful and non-aggressive species to ensure a harmonious community. Breeding Cardinal tetras can be a challenging but rewarding experience for experienced hobbyists, and patience and ideal conditions are key to success. Overall, Cardinal tetras are a stunning and lively species that can enhance any aquatic display with their vibrant hues and lively behavior.

Frequently Asked Questions

What is the ideal tank size for Cardinal Tetras?

When setting up a home for Cardinal Tetras, a 20-gallon tank is the minimum recommended size for a small group. Opting for a larger tank is even better, as it helps keep water conditions stable while offering plenty of room for your fish to swim.

How many Cardinal Tetras should be kept together?

Keep in mind that Cardinal Tetras are schooling fish, which means they thrive in groups of at least 6-8 individuals. By maintaining a larger group, you'll not only help your fish feel safer but also encourage them to display their fascinating natural behaviors.

What water parameters do Cardinal Tetras require?

Cardinal Tetras thrive in water temperatures between 73°F and 81°F (23°C and 27°C), a pH between 5.5 and 7.0, and soft to moderately hard water with a hardness between 1 and 10 dGH.

What do Cardinal Tetras eat?

Cardinal Tetras are omnivorous and require a varied diet. Feed them a mix of high-quality flake or pellet food, along with live or frozen foods such as daphnia, brine shrimp, and bloodworms.

Are Cardinal Tetras compatible with other fish?

Yes, Cardinal Tetras are generally peaceful and can coexist with other similarly sized, non-aggressive fish species. Ideal tank mates include other small tetras, rasboras, corydoras catfish, and small plecos.

How can I differentiate between Cardinal Tetras and Neon Tetras?

Cardinal Tetras have a red stripe that extends the entire length of their body, whereas Neon Tetras have a shorter red stripe that covers only half of their body length.

How long do Cardinal Tetras live?

With proper care and optimal tank conditions, Cardinal Tetras can live for 4 to 5 years.

How do I breed Cardinal Tetras?

Breeding Cardinal Tetras can be challenging, as they require specific water conditions, such as very soft, acidic water, and a dimly lit environment. Use a separate breeding tank, and separate males and females before introducing them for spawning.

Do Cardinal Tetras require a planted tank?

While not strictly necessary, a planted tank is highly recommended for Cardinal Tetras. Live plants provide hiding spots, improve water quality, and create a more natural environment that closely resembles their native habitat.

Can Cardinal Tetras change color?

Indeed, Cardinal Tetras can undergo color changes as a result of several factors, such as stress, illness, or alterations in water conditions. If you observe your Cardinal Tetras experiencing a loss of color, it's important to examine the water parameters and keep a close watch on their health.