Dario dario (aka Scarlet Badis, Scarlet Gem Badis) are one of my favorite species of freshwater fish. They are ideally suited to low-tech nano tanks. The males have a beautiful coloration and pattern, primarily red with blue vertical stripes. Submissive males can have drab colors, and females are shades of grey. They are a fascinating, shy little micropredator.
Care Level: Moderate (diet considerations)
Preferred Water: pH 6.5 to 7.0, soft to moderately hard water
Ideal Temperature: 65°F to 78°F (18°C – 26°C)
Maximum Size : 0.5″ to 0.7″ (1.3 cm to 1.8 cm)
Average Lifespan: 4 to 6 years
Dario dario are native to shallow, slow moving streams of east India. They prefer waterways with dense vegetation, where they can be protected from larger fish and other predators.
Dario dario are true micropredators. They feed on small prey like copepods, worms, and insect larvae. In captivity, they will usually not readily accept flake or pellet food. When I kept them years ago, they would only eat live food. Daphnia, copepods, other small aquatic crustaceans, and different kinds of small worms are great food for these fish. Some say they can be trained to adapt to flakes or pellets, but I had no such luck. They do prefer live prey, but will sometimes accept frozen foods. I have read that they can develop complications with a diet heavy in bloodworms or tubifex worms, so it is probably best to avoid these.
Males tend to be aggressive towards each other, so if you are trying to breed them, it is best to keep only a single male with one or more females. When the males are preparing to mate, they will begin to establish territories. If you have more than one male in an aquarium, it is recommended that each have room enough for a territory of about 4.5 square inches on which to spawn. They prefer areas with ample cover and access to the substrate, where the eggs will reside.
Once territories have been established, the males will begin a courtship display, showing off their beautiful blue finnage. If a female is enticed into the territory, she will scatter her eggs on the substrate, beneath an overhanging structure like a leaf or outcropping of wood. The male will then fertilize the eggs and chase off the female. The male will then be left alone to care for the nest site.
In approximately two to three days, the eggs will have hatched and the fry will be free-swimming. Once their yolk sacs have been depleted, they will feed on infusoria. For an optimal yield of fry, it is advised to remove the substrate containing the eggs to a separate container, because adults will readily feed on the tiny fry.
In the Aquarium
I think Dario dario are really fascinating little fish, and I think they are perfect for nano aquariums. Because of their sexual dimorphism, it is uncommon to see females of this species sold in shops. I suppose they are just too small and bland looking, though I have seen them on display one time. They may have come from a local breeder.
Scarlet Badis do not require much intensive care, as long as their live food preference is met. If you can manage to train them on flake or pellet food, then you’re rockin’ it. The only other potentially difficult aspects of these fish is their funny combination of shyness and aggression. In community tanks, these fish can easily be intimidated by larger species to the point of never venturing out of concealment. This can lead them to underfeeding and potentially starvation. Their small size also puts them at risk to being eaten by larger fish. On the other hand, male Dario dario can be quite aggressive towards each other. So it is recommended that you do not keep two males together in the same aquarium, unless there is ample space for separate territories. Each male will want adequate cover and vegetation to call his own. If there is not enough space to go around, one male can easily harass the other to death. I’ve read recommendations that say each fish should have access to a territory space of at least eight inches in diameter.
In my experience, the best style of aquarium for Dario dario is a Walstad Method aquarium. A low-tech, rich soil substrate often encourages tiny crustaceans and worms to thrive. When I kept Scarlet Badis, I never had to feed them any food myself. I simply feed some basic fish food to the aquarium, which fed the population of tiny critters, which in turn were eaten by the fish. It was a very well balance and effective system. Otherwise you would need to keep a separate culture of worms, copepods, amphipods, or brine shrimp for your Dario dario’s needs.
Let me know what you think of this species profile.
Featured image credit: Brent Stephenson. Source: flickr.com creative commons