Cardinal Tetra

The Cardinal Tetra is a tiny, ornamental river fish from the Amazon River system that is highly popular in the aquarium trade, and are known for their shimmering coloration. However, they are not as popular as the neon tetra since it is more difficult to breed the former.

This member of the large tetra family is a hardy fish that enjoy living with other fish species, but need to be kept in a medium to large school comprising of at least six individuals. It not merely makes them live comfortably, but also adds a ‘glow’ to your fish tank, literally.

Quick Biological Information

Profile	Information
Scientific Name	Paracheirodon axelrodi
Other Names	Large neon tetra, red neon, roter neon
Type	Tropical freshwater fish
Conservation Status	‘Least Concern’
Behavioral Characteristics	Social, peaceful, community-friendly
Physical Traits	Flat, leaf-shaped body with the upper part above the lateral line, the fins, and the tail being translucent
Body Colors	The body is divided by a thick and iridescent blue-green lateral line mixed with metallic (golden and silver) hue, while the part below the line is dark red
Length/Size (how big do they get)	Size varies from small to relatively larger ones (known as ‘jumbo’); full-grown adults are around 2 inches (5 cm)
Weight	0.004 oz (0.13 gr) approx.
Lifespan/Life Expectancy (how long do they live)	Around 4 years
Skin Type	Scaled
Clutch Size	Up to 130 individuals (in the wild)
Sexual Dimorphism	No significant differences, with the females being slightly wider and larger than the males
Predators	Fish, eels, crustaceans
Feeding/Diet (what do they eat)	Omnivorous; in the wild, they consume algae, fungus, plankton, fruit, fish larvae, fly larvae and pupae, ants, mites, newborn shrimps, etc.
Range/Distribution	Around the Amazon Basin, in the upper parts of South America’s Orinoco and Negro rivers, covering Brazil, Colombia, and Venezuela
Natural Habitat (where do they live)	Inland freshwaters of the forest streams and rivers

Setup & Care Sheet: How to Care for Cardinal Tetras

Tank Size/Water Amount	A minimum of 20 gallons of water is required for keeping in community tanks with a shoal/school of other different species
pH	Below 2.9 or above 8.8
Water Hardness	Up to 4 dGH
Care Level	Moderate
Water Temperature	78 – 81 °F (23 – 27 °C)
Water Movement	Slow-moving or standing
Lighting Level	Low or dim
Carbonate Hardness (KH)	2 – 6
Compatibility with Tank Mates	Friends: Other species of tetras (like the Congo, lemon, diamond, rosy, gold, pretty, Adonis, or neon tetras), rasboras, danios, and small to medium size species from the catfish family; Enemies/Predators: Large fish that are common in fish tanks, like the discus, larger angel species, some gouramies like the blue gourami; Also, those that naturally prey upon smaller species, like cichlids, snakeheads, etc.
Tank Bed	A mixture of silica sand and small gravel
Growth Rate	Modest (assumes full adult coloration after 8 – 12 weeks)
Environment & Substrate Type	Lots of live green plants; Plenty of hiding places
Best Food Types	Live food (mainly insects, larvae, bloodworms or brine shrimps), flakes, and pellets
Feeding Frequency	2 – 4 times a day
Tank Position	Top to mid-dweller

FAQs

Q. What is the difference between neon tetra and cardinal tetra?

In a cardinal tetra, the upper portion of the body is vivid blue or blue-green, and the entire lower part has a bright crimson coloration. In a neon tetra, though the upper portion of the body has a luminous blue color, the red in the lower part is centered only around the tail rather than all over the lower half.

Q. What does it mean when you see white spots on cardinal tetras?

White spots in cardinal tetras are not uncommon, and this disease is usually caused by the bacteria Ichthyophthirius multifiliis (commonly called ‘ich’). The symptoms include white patches on the body and the fins, while you may often find the affected fish rubbing and scratching themselves against hard objects.

In such cases, you can talk to an aquarium expert and use an antibacterial solution accordingly, depending upon the intensity of the spots. If left untreated, your fish might die within a few days.

Q. How many cardinal tetras should be in a group?

Cardinal tetras are gregarious fish and prefer moving in packs. So, to form a comfortable group, a minimum of five of these tetras is advisable.

Did You Know

• Cardinal tetra gets its name from the vivid red coloration (‘cardinal red’) below its lateral line.
• They are mostly confused with the neon tetras; however, the main difference between the two is that, the cardinal tetras are larger than the neon tetras, as also, the red mark in their body runs across their length, unlike the latter that run halfway (belly to tail).
• Interestingly, though they may get stressed if they are alone, you may not see them forming tight packs unless there is a threat.
• Cardinal tetras are available in varying phenotypes, like the ‘gold’ and the ‘silver-blonde’ types, which are found in the Rio Negro drainage system, both of which have less blue coloration in their longitudinal stripe.