Freshwater Fish

Ruby Tetra – Axelrodia riesei: Care Guide

Ruby tetras are beautiful freshwater fish that can be a joy to keep. With its bright colors and small size, this species will create a great flash of color in your tank.

This guide will go over everything you need to know about proper Ruby tetra care, so you can be ready when you decide to get one yourself!

Species Summary

The ruby ​​tetra (Axelrodia riesei) is a lesser-known member of the Characidae family. A relatively new find compared to other established fish, this species first came to prominence in 1988.

These fish are exclusive to the upper Meta River in Colombia. They are found in smaller tributaries and streams around the area, but do not venture too far beyond the confines of their ancestral waters. For this reason, ruby ​​tetras are not as widespread as other types of tetras.

If you’re lucky enough to get your hands on some ruby ​​tetras, you’ve got years of fun ahead of you! Thanks to their bright coloration and schooling nature, these fish are a sight to behold in well-decorated tanks. Small and peaceful in nature, they make great additions to nano tanks and small aquariums.


Despite their small size, ruby ​​tetras pack a big visual punch!

They have the characteristic torpedo-shaped body of other tetraspecies. The head is rounded and full. Meanwhile, the end of the tail tapers to a fine caudal fork.

The fins are mostly pale. However, most specimens have subtle streaks of iridescent blue at the tips of their fins. The small detail creates a beautiful effect in the light.

The rest of the body is orange-red. The only exception is a black spot on the tail fin.

In the wild, ruby ​​tetras are quite vivid. While still beautiful in captivity, most fish experience some dullness.

Author’s Note: Males and females look nearly identical. The main difference between the two is the size and overall girth. Males tend to be slightly smaller. Not only that, but females exhibit a rounder shape around the midsection.

Life expectancy

Under good living conditions, the average lifespan of the ruby ​​tetra is between five and ten years.

As always, there are no guarantees with life expectancy. Unexpected illnesses and genetic diseases could shorten their lives. That said, the quality of care you provide has a huge impact on your potential lifespan.

Providing top-notch care can reduce the chances of common aquatic illnesses, allowing your ruby ​​tetras to reach the end of their natural lives while staying healthy. Fortunately, this freshwater species is fairly easy to care for (more on that later).

Average size

These fish are at the smaller end of the size spectrum. The average size of an adult ruby ​​tetra is no more than 1.6 inches long. It is quite common that many never reach this length.

Author’s Note: Due to their small stature, these make excellent nano fish for small tanks. However, you need to be careful around community settings and potential predators. These fish become targets very quickly!

Ruby Tetra Care

In general, ruby ​​tetra care is no more challenging than any other tetra species. However, they do have some unique needs that you need to address. These freshwater fish are smaller and more delicate than other species in the trade, creating different challenges every time.

Fortunately, overcoming these problems is very easy if you adhere to the following care guidelines.

tank size

The first thing you will need is a properly sized tank. Most experts agree that the ideal ruby ​​tetra tank size should be no smaller than 10 gallons.

Author’s Note: Technically speaking, individual fish can do well in smaller aquariums. However, ruby ​​tetras are a bank species. To live comfortably, they must stay in groups of at least six fish. A 10 gallon tank is enough to hold up to ten fish.

If you want to keep more than that, make it bigger! These fish can create impressive displays in massive groups.

water parameters

One of the most important parts of providing excellent ruby ​​tetra care is replicating the water conditions of its natural environment.

This species comes from streams and blackwater tributaries. They prefer warm waters rich in nutrients. Slight acidity and relatively soft water are preferred.

Unlike other tetras, rubies can be a bit finicky. Remember, they only come from one body of water in South America. As a result, this species does not have the resistance that others have.

Stay on top of water parameters and use an aquarium test kit regularly to ensure conditions are stable.

  • Water temp: 68°F to 82.4°F (aim for the low 70s)
  • pH levels: 5.0 to 7.0 (lean toward acidic water)
  • Water hardness: 3 to 12 KH

What to put in your tank

When it comes to decorations, you have a lot of wiggle room! Again, it’s best to stay true to this fish’s natural environment, but there are many different ways to get there.

Start with a layer of sand substrate. Sand looks a lot like silt and mud from the river bed. Ruby tetras rarely venture to the bottom of the tank as they stay in the upper and middle parts of the water column. However, the sand will provide a soft surface for them to rest on if they explore the depths of their tank.

On top of the substrate, add some natural-looking decoration. You can lay down some pieces of driftwood, smooth rocks, and other organic pieces.

Author’s Note: Many aquarists also recommend dropping a few Indian almond leaves onto the substrate. The leaves will slowly break down and release tannins into the water. Not only does this help lower the pH, but it also recreates the leaf litter that lines the depths of their natural habitat.

Another essential are the plants. Ruby tetras love to swim through plants. They also wear them for protection and comfort.

Add a mix of floating plants to create a lively environment. Be sure to leave enough open space for swimming.

For the team, you can keep things simple. Use a standard filtration system that produces a slow flow of water. Ruby tetras also prefer low-light environments, which plants can help create.

Possible common diseases

Ruby tetras are not immune to disease. They can suffer from all the usual ailments that affect freshwater species.

Some of the more common diseases to watch out for include Ich, skin flukes, bacterial infections, and parasitic infections.

In most cases, these diseases arise from stress and poor living conditions. Maintain the water parameters and do your best to keep them as stable as possible. Ruby tetras can handle some slight fluctuations here and there, but significant changes are sure to cause some health issues.

Author’s Note: If you notice one of your fish struggling, quarantine it. Many of the common health problems are easy to treat with over-the-counter medications.

Food and Diet

These fish look small and innocent. But in the wild, they are considered micropredators. They feed on small invertebrates, insects, and anything small enough to fit in their mouths.

In captivity, they are best fed a varied diet consisting of high-protein foods. Small flakes and granules work well.

However, it’s also a good idea to include some live foods. Ruby tetras will happily eat Artemia, micro worms, Tubifex, minced blood worms, and baby brine shrimp. They will accept freeze dried food, frozen food and even live food.

Feed your ruby ​​tetras several times a day. In order not to spoil the water, just provide enough food that your fish can eat in about two minutes.

behavior and temperament

Ruby tetras are peace-loving fish that want nothing more than to play and have fun.

They are a kind of shoals. That means they stick together to explore the tank. However, the fish sometimes go off and do their thing.

Naturally somewhat shy, ruby ​​tetras can take a while to come out of their shell. This is especially true if there are other fish in the tank. They may be a bit anxious when they are first introduced to a new environment.

Give them some time and space. Eventually the tetras will begin to display more friendly behaviors.

You may see them swimming through plants and hiding in the shadows. When in a large group, these fish will swim through the environment as one.

Author’s Note: With many ruby ​​tetras in the same tank, you may see smaller clicks form. Groups of males can sometimes create defined territories that they will defend. When this happens, don’t be surprised if you see some light combat.

Ruby Tetra Tank Mates

While the ruby ​​tetra is a peaceful fish, you have limited options for tank mates.

The small size of these fish makes them instant targets. Even in a community of non-aggressive inhabitants, ruby ​​tetras can be mistaken for food.

Your best option is to keep ruby ​​tetras in large groups. They thrive when surrounded by others of the same species. A group of at least six fish is a must, but you can always go bigger.

Beyond other ruby ​​tetras, you can try:


Raising ruby ​​tetras is not too complicated. In mature tanks spawning sometimes occurs naturally without any intervention!

However, those looking to maximize survival rates should breed these fish in a separate tank. Ruby tetras do not guard the eggs or show any parental instincts, so you must provide some separation between the adults and the fry.

In a separate 10-gallon tank, create an environment similar to the main aquarium. Add plenty of fine-leaved plants. Ruby tetras scatter eggs, so you need plants to provide protection.

A bit of leaf litter is also recommended. The remains have microorganisms that the fry can eat once they emerge from the egg.

Keep the lights low and turn the temperature up a few degrees above the main tank. When adding adult fish, use more females than males.

It shouldn’t take long for playback to occur. The females will spread their eggs throughout the tank. When this happens remove the adults and let the eggs incubate in peace.

After a couple of days, the eggs hatch and eat the egg sac. Once they are big enough, you provide infusoria, brine shrimp, and powdered fish food.


Ruby tetra care is pretty manageable, no matter how much experience you have. This freshwater species requires little maintenance and is so much fun to watch!

We hope you will consider this fish for your next freshwater aquarium. If you have any questions just let us know!

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