Scarlet Badis – Species Profile & Facts

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The scarlet badis is one of the best choices for nano tanks. These fish are tiny even for nano tank standards, vividly colored, and with a matching temperament that makes them unfit for community tanks.

This isn’t necessarily a downside, because a handful of scarlet badis will create a thrilling setup by themselves. But are these fish easy to care for, and how should you craft their environment to keep them comfortable and calm? We’ll get into this and much more in today’s article. So, let’s get it started!

What is a Scarlet Badis?

The scarlet badis (Dario Dario) belongs to the Badidae family and ranks as the smallest percoid fish we know. Percoids are fish belonging to Percoidae, a superfamily of small fish containing more than 3,300 species.

The scarlet badis’s point of origin is the Brahmaputra River in India, although there have been some sightings in other parts of the country over time. The fish’s habitat is pretty small in this sense, making it rather difficult to collect from the wild.

Fortunately, the scarlet badis has no difficulties breeding in captivity, so long as their environmental conditions are right.

Scarlet Badis Requirements

This fish is typically easy to satisfy in terms of environmental requirements. They don’t need much space but do require a specific setup and clear waters to thrive.

Tank Size & Setup

You need at least 10 gallons to accommodate a group of scarlet badis. These fish aren’t exactly social, so don’t try to integrate them in a community setup. However, they do appreciate the company of each other, provided there’s enough space for all of them.

The scarlet badis is territorial and aggressive and can cause tensions if there isn’t sufficient space for all fish. This happens especially during mating when the males are particularly snappy and violent. Plus, the fish’s habitat should contain a lot of plants and rocks, along with a sandy substrate to mimic their natural environment.

All these elements will take up space, leaving little for the badis to use for swimming. So, while the minimum recommended tank size is 10 gallons, I would recommend 20 gallons instead. Such a setup is enough to accommodate a group of 6 scarlet badis, 1 male and 5 females.

If you intend on housing more than one male per tank, go for a 30-gallon aquarium instead. Males are particularly territorial and violent towards each other, so you shouldn’t keep more than one per tank. Unless there’s sufficient space for the males to avoid each other easier and the 30-gallon piece fits right in.

As a closing note, avoid tanks smaller than 10 gallons. These aquariums experience faster water quality degradation, and scarlet badis are extremely sensitive to subpar water parameters. Plus, there isn’t sufficient room for a properly-sized badis group.

Water Requirements

Aim for water temperatures around 72 to 79 °F, a pH of 6.5 to 7.5, and water hardness of 10-20 dGH. These are ideal parameters for the scarlet badis and a clean and fresh environment. These fish are notoriously sensitive to poor water conditions, causing them to experience weaker immune systems and higher vulnerability to fungal and bacterial infections.

So, regular maintenance, substrate vacuuming, and water changes are necessary to preserve the system’s stability and keep it clean and fresh. Be careful when setting up the filtration system. The filtration unit may be necessary, but it also comes with risks along the way. The scarlet badis is a small fish than can easily get sucked into the system.

It also doesn’t like strong water currents, so the filter should come with adjustable power output.

Feeding and Diet

Scarlet badis are micro-predators, feeding mostly on plankton, insects, insect larvae, and small invertebrates in the wild. Their diet in captivity should mimic their natural feeding tendencies. Provide your scarlet badis with a meat-based diet, encompassing life and frozen food.

The scarlet badis will consume anything that contains animal protein, including brine shrimp, daphnia, white worms, bloodworms, and even pellets and dry flakes. You should introduce pellets and flakes early in their diet so that the fish become accustomed to them sooner. This will prevent them from rejecting these foods as adults.

Always prepare the food for your scarlet badis before feeding. These are tiny fish that cannot take large bites, so chop the food into smaller pieces to help them eat better. The classical homemade protein paste works wonders in this sense, although it tends to foul the environment fast.

Don’t overfeed your scarlet badis; only provide sufficient food for them to eat in a couple of minutes, and remove the leftovers immediately. Remember, small tanks require more maintenance as the environment gets dirty faster than in larger aquariums.

Do Scarlet Badis Need a Heater?

While the scarlet badis don’t need excessive water temperatures, they do require stable water parameters nonetheless. Their water temperature should remain stable in the 72-79 °F range. Frequent or massive temperature fluctuations can stress out the fish, lowering their immune system and making them prone to infections and parasites.

Have a tank heater in place, especially if you live in an area with frequent temperature fluctuations.

Do Scarlet Badis Need a Filter?

Yes, scarlet badis need a good filtration system to keep their habitat clean and well-oxygenated. It’s good to remember that the filtration system has a greater impact in a nano tank than a normal-sized one. While the filter’s benefits cannot be overstated, there are some downsides to discuss as well.

When choosing your right nano filter, consider the following:

  • Adjustable flow rate – The filter should have an adjustable flow rate to allow you greater personalization capabilities. Scarlet badis hate strong water currents, and so do plants. The adjustable flow rate allows you to adjust the filter’s output power to match the system’s requirements.
  • Go below the recommended power – The standard recommended flow rate for a nano filter is 100 GPH (Gallons Per Hour) for a 10-gallon tank. But this varies. You don’t need such a high flow rate in overplanted aquariums which is how your scarlet badis tank will be. So, bring the flow rate down to 50 or 45 GPH and monitor the results over a couple of days. You can adjust the flow rate according to the findings.
  • Secure the filter’s intake – Depending on the type of filter you’re using, you may need to secure the filter’s intake. The intake is generally small but may not be small enough to prevent the badis from getting sucked in. Cover the filter’s intake with a sponge to prevent that, and remember that this will also reduce the flow rate significantly in the process. Check the sponge regularly and clean or replace it frequently to prevent clogging due to the accumulation of muck and dirt.

You should also position your filter’s output and intake so that they won’t bother the fish or the plants. Keep them away from the substrate to prevent them from sucking in or stirring the particles.

How Much do Scarlet Badis Cost?

Scarlet badis are usually sold in bulks of 3-6 and can take you to $12-$35 per batch. The price varies based on the marketplace and the fish’s size, age, and coloring. These are cheap fish, making them great for novice aquarists who can afford to lose them during the learning process.

What is the Lifespan of Scarlet Badis?

In ideal conditions, the scarlet badis can live up to 3-4 years in captivity. By ‘ideal conditions,’ I mean:

  • Optimize diets for ideal nutritional intake
  • Sufficient space to ensure maximum comfort and low fish-to-fish tensions
  • A proper layout with plenty of live plants, hiding areas, and sufficient swimming space
  • Compatible tankmates (avoid large, aggressive, or bullying fish)
  • Preferably one male per tank to prevent territorial aggression
  • A robust cleaning and maintenance routine for a healthy and stable aquatic system

These factors show that you can control your fish’s lifespans to a certain degree.

How Big do Scarlet Badis Get?

Scarlet badis males only grow up to 0.8 inches, while females won’t go over 0.5 inches. This makes the scarlet badis small even by nano standards. The fish’s size can be an advantage, though, as it allows you to stock more in the same tank.

The downside is that there are few compatible tankmates for the badis. Most fish are too large and will eat the scarlet badis as a result.

Are Scarlet Badis Aggressive?

Yes, these are carnivorous predators, so they’re bound to be aggressive. They are also territorial and compete over food and females with a similar determination. Scarlet badis males are especially violent towards one another, which is why you should only keep one per tank.

The fish’s violent demeanor is also a problem towards other fish species, as the scarlet badis doesn’t discriminate when it comes to violence. The badis can’t really hurt other fish due to their small size, but they can bully and stress them out. Constant nipping can also cause microtears in the skin, making the bullying victim more predisposed to infections.

Scarlet Badis Tankmates

I don’t say this too often but avoid any tankmates altogether. Few fish are compatible with the scarlet badis due to the differences in size and behavior. The closest fish you can get to a compatible tankmate is the celestial pearl danio. This fish only grows up to 1 inch and is generally friendly and peaceful.

Other potential tankmates are adult cherry and amano shrimps and adult nerite and mystery snails. This is realistically the extent of the viable tankmates for your scarlet badis.

Are Scarlet Badis Good for Beginners?

Not exactly. Scarlet badis are more suitable for experienced aquarists or at least those with some knowledge of nano tanks and nano fish. The scarlet badis itself is a more sensitive specimen than most fish, requiring more intensive care and maintenance. This fish is prone to health problems due to poor water conditions, and nano tanks are more demanding in terms of maintenance.

So, I would recommend skipping this species if you lack the time or knowledge to keep the fish’s habitat in optimal condition.

How to Tell if Scarlet Badis is Male or Female?

Fortunately, it’s quite easy to sex the scarlet badis. Males are almost 30% larger than the females and display more colored bodies with intense color patterns. Scarlet badis males have thick vertical red stripes covering the entire body, including the dorsal and ventral fins.

Females are smaller and lack the male’s trademark red stripes. Their fins are also smaller.

How do Scarlet Badis Breed?

While the scarlet badis are easy to breed in theory, they require specific environmental conditions to ensure the success of the process. The mating and breeding themselves unfold as such:

  • The male engages in the mating dance to attract the female; this consists of shaking and specific body movements meant to get the female’s attention
  • If the female falls for the male’s charms, it will follow it for mating purposes. If not, the male will chase the female to help her make up its mind
  • Once the female is ready, it will enter the male’s territory and lay up to 80 eggs
  • The male will fertilize the eggs and chase the female away
  • The male will protect the eggs until they hatch, which typically lasts up to 2-3 days
  • The resulting fry will feed on the egg yolk for the first several days to a week

There are 2 important notes here:

  1. Don’t move the fish – Once the mating process has begun, you should not relocate the adult fish into another tank. The scarlet badis male has a designated territory where it feels safe and invites the female for breeding. If you move them into a nursing tank, the mating process can cease completely.
  2. Relocate the fry – Keep the fry in the main tank for the first several days until they’re done consuming the egg yolk. Once they start swimming freely, move them into a nursing tank. This will increase their survival rates as it prevents them from being eaten by the adults.


Scarlet badis are small and cute fish that come with a colorful presence and an even more colorful personality. They’re generally easy to keep, but they require specific environmental conditions to thrive. Above all, they need clean and healthy waters, so be ready for regular tank maintenance and a tight water change schedule.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.
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