If youโre looking for fish to keep in a nano aquarium, your options will unfortunately be somewhat limited. Most species just get too big! That being said, there are still a few fish out there that will do well in a smaller tank. Our favorite? Dario dario, better known as the scarlet badis.
Keep reading for everything you need to know about the scarlet badis, where itโs from, and what yours will need to thrive!
| Name (Common, Scientific) | Scarlet badis, Dario dario* |
| Minimum tank size | 10 gallon |
| Minimum group size | 1M 2F |
| Temperature | 64.5-78.5 ยฐF |
| pH | 6.5-8.5 |
| Difficulty level | Easy |
Scarlet badis description & natural habitat
Description
Despite their very small size (only about 1โ), male scarlet badis are not easy to overlook. Their bright orange-reddish color is interrupted by seven blue, iridescent bars on the body. Thereโs also some iridescence on the fins, which they will gladly show off when confronted with a female or a male intruder to their territory.
Females of the species are a lot less spectacularly colored than the males. Theyโre also smaller and their fins stay shorter, which is why they can be more difficult to find in the aquarium trade.
These shimmery little fish belong to the Badidae or chameleonfish, a family of small fish belonging to the larger superfamily Percoidea (โperch-likeโ or perciformes, though technically not true perches). Their common name of โbadisโ makes them easy to confuse with their equally colorful cousin, Badis badis, but that oneโs blue rather than red.
Indeed, todayโs subject was thought to belong to the genus Badis for a long time. It was called Badis dario until scientists reclassified it in 2002!
Natural habitat
The scarlet badis is naturally found in India (West Bengal, Assam) and possibly into neighboring Bhutan. It inhabits small streams and tributaries that flow into the massive Brahmaputra system, but doesnโt occur in the river itself.
This speciesโ favorite waters are known to be shallow (not much more than 2ft) and very clear. Theyโre also heavily vegetated with both floating and aquatic plants, and feature a fine gravelly to sandy substrate.
Did you know? The IUCN Red List considers Dario dario to be a species of Least Concern. This means itโs not currently threatened in the wild. This being said, the organization does note that its natural habitat is under pressure due to deforestation and other human activities.

Scarlet badis aquarium
Because the scarlet badis is a true microfish, itโs a popular choice among nano aquarists and aquascapers. You can keep yours in a tank with a volume of 10 gallons or up, although the species will also do fine in a larger aquarium.
Another nice thing about Dario dario is that we know exactly what kind of environment it needs to thrive: shallow and with an abundance of plants. Itโll appreciate something similar to its natural habitat in the aquarium. In fact, yours might become shy, pale, and withdrawn if you donโt offer enough cover.
To keep your fish happy and feeling at ease, choose a soft substrate. Add lots of (floating) plants (Limpnophila, Vallisneria, Hygrophila and other species it might encounter in the wild would be ideal), and include plenty of decor in the form of rocks and driftwood. Keep the filter flow calm and donโt blast your fish with overly bright lighting.
Water parameters arenโt too much of an issue, as the scarlet badis does well in a wide range of pH and hardness levels. The same goes for temperature. The most important factor is stability: avoid sudden swings in water quality.
Make sure, as always, that the tank is fully cycled before adding your Dario dario or any other livestock. Keep up with weekly water changes and other aquarium maintenance.
Tankmates
Although scarlet badis are technically predators, their size obviously makes them prey as well. Theyโre a little timid and donโt combine well with larger or more assertive aquarium fish species. Many aquarists prefer keeping them in a single-species set-up, especially in nano tanks.
If you do want to add tankmates, go for peaceful fish that prefer similar water values. Small tetra species, pygmy Corydoras or microrasboras work well. They wonโt outcompete the badis for food, but are also unlikely to be bothered by it.
As for their own kind, as weโve mentioned, it can be difficult to find female scarlet badis in your local aquarium store. They simply arenโt sold as much due to their less spectacular coloration and finnage.
This is a pity, because youโll enjoy your scarlet badis the most if you keep them in a pair or harem. Having females around allows the male to show off his courting skills and beautiful coloration. In a 10-gallon aquarium, something like 1 male and 2 females should work fantastically.
The males are quite territorial and shouldnโt be kept together unless you have a larger (20+ gallon) aquarium. Be sure to set up coconut huts or upturned flower pots for them on opposite sides of the tank, so they can establish their own territories.

Scarlet badis diet
Generally speaking, scarlet badis are not a demanding species. Theyโll do fine in the care of a beginning aquarist. The most challenging aspect of caring for them in the aquarium is their diet: these micropredators naturally feed on anything thatโs tiny and moves. In captivity, they can have trouble adjusting to pellets and flake foods.
If youโd like to keep scarlet badis, itโs a good idea to set up a live food culture (which we think is something any aquarist would do well to look into anyway!). All fish will appreciate being able to hunt tiny live fare like freshly hatched brine shrimp, Daphnia, grindal worms, and similar small critters.
Breeding scarlet badis
If youโre interested in breeding your fish, youโll be delighted to hear that scarlet badis make a great choice for aspiring aquaculturists! They breed pretty readily in the aquarium. In densely planted tanks, you may find offspring popping out of the greenery without any interference on your part.
To give the fry better chances of survival, itโs best not to keep your scarlet badis with any tankmates. Feed plenty of nutritious live and frozen foods and keep the water quality high. Youโll soon see the male starting to show off and attempting to entice females into his territory.
The eggs are deposited on plants or similar surfaces, so itโs helpful to add some Java moss or spawning mops. These are easy to take out of the tank so you can raise the fry separately (which prevents predation by the parents). Do keep in mind that the babies are tiny, so youโll need to have an infusoria culture ready to feed them once theyโve absorbed their yolk sacs.
Conclusion
Scarlet badis are the perfect addition to a small (or big!) jungle-style aquascape, which in turn makes an amazing eyecatcher in any home or office. FantaSEA Aquariums has experienced freshwater aquascapers ready to design, set up and maintain your tank for you.
If youโd like all the enjoyment and none of the hassle of owning an aquarium, simply contact us here with your ideas. Weโll get working on your dream tank ASAP!
Sources & further reading
Kullander, S. O., & Britz, R. (2002). Revision of the family Badidae (Teleostei: Perciformes), with description of a new genus and ten new species. Ichthyological Exploration of freshwaters, 13(4), 295-372.
Rรผber, L., Britz, R., Kullander, S. O., & Zardoya, R. (2004). Evolutionary and biogeographic patterns of the Badidae (Teleostei: Perciformes) inferred from mitochondrial and nuclear DNA sequence data. Molecular Phylogenetics and Evolution, 32(3), 1010-1022.










