One of the plainer-looking danio species, the pearl danio, can make a great addition to aquariums lacking in activity.
These top-swimming fish are easy to keep and get along with most other community fish. They are also the perfect choice for aquarists interested in spawning different freshwater species.
Keep reading to find out everything you need to know about pearl danios and how to keep these iridescent fish in your aquarium!
Brachydanio albolineatus is commonly known as the pearl danio. These popular fish are named for their pinkish-white iridescence that shimmers when they move.
Though these fish are known as danios, they have been removed from the true Danio genus.
Pearl danios have been established as differing enough from the other species within these groups to put them in the Brachydanio genus. The Brachydanio genus is believed to contain some of the most original species of these fish.
Pearl danios, Brachydanio albolineatus, should not be confused with the similarly-named celestial pearl danios, Danio margaritatus. Though the care requirements for both pearl danios and celestial pearl danios are very similar, these two fish species are unique in their own ways!
Check out this guide for a complete care sheet on celestial pearl danios.
Pearl danios can be found throughout southeast Asia, specifically from Myanmar to Laos and Sumatra in Indonesia. Populations have also been reported in the Mekong River, home to some of the largest fish on the planet.
However, pearl danios prefer hill streams with cold, fast-moving water. These waters are clear, and these fish can be seen swimming in groups just below the surface, waiting to catch any insects that might land on the surface.
As we’ll see, you will need to replicate these conditions in the home aquarium.
The pearl danio is named for its pinkish-white iridescent color that resembles the shine of a pearl. These aquarium fish are very light in color but might have a noticeable light orange line that runs from behind their gills to their tails.
Pearl danios are small, peaceful fish. They only grow to be about two inches in length (5.1 cm).
Female pearl danios are usually slightly larger than males and have a rounder abdomen. Differences in males and females become especially apparent during spawning seasons, as males intensify in color and females become plump with eggs.
Pearl danio tank requirements
Danio species are some of the easiest fish to keep in the entirety of the aquarium hobby. These nano fish are almost immune to beginner’s mistakes and will quickly bounce back from poor water conditions.
You want your fish to shine, though! Even though pearl danios are easy to maintain, they need to be kept in the best setup possible to experience their true nature.
Pearl danios need at least a 10-gallon (37.8 L) aquarium; a bigger, longer tank would be much better as these fish are incredibly active.
They can be kept on either a sand or gravel substrate. A sand substrate will allow for a more natural look, but it is rare to see your pearl danios interact with the substrate on any occasion.
In the wild, these fish are found swimming below the water surface in fast currents. Your pearl danios will especially enjoy a moderate to high water flow from an aquarium filter or powerhead.
Because these peaceful nano fish are so active, they will quickly digest food and create waste. A filter rated for at least 2x the size of the tank is strongly recommended to help keep tank water parameters stable and provide additional flow.
Most danios are considered coldwater fish species, preferring cooler temperatures a little below tropical conditions. Pearl danios are different. Instead, pearl danios prefer a water temperature closer to the ideal conditions of other tropical fish, needing a constant range of 73-77° F (22.8-25.0° C). An aquarium heater is strongly recommended to raise temperatures and keep them steady.
Otherwise, most danio species, including pearl danios, are relatively hardy fish. They should be kept in zero ppm ammonia, zero ppm nitrite, and minimal nitrate levels, though they can survive temporary, imperfect parameters.
Pearl danios will also do best at a neutral pH of 7.0.
Pearl danio tank mates
These fish will look their best in a well-planted community tank with other featured fish. Pearl danios aren’t the most eye-catching fish, but their simple colors can be used to accent bigger and more colorful fish.
Some of these tank mate options include:
- Peaceful barbs
These fish will also do great in a planted aquarium featuring various shrimp species, like cherry shrimp (Neocaridina davidi).
In general, it’s best to keep these fish out of reach of aggressive fish that could easily eat them. That said, some hobbyists have had luck making interesting predatory pairings.
It is not unheard of to have something like a piranha and danio combination in a larger tank. In theory, the danios are too fast and active to appeal to a well-fed piranha.
Of course, those danios are more than likely to be eaten as time goes by, but a school of danios can become self-sustaining due to quick and easy breeding.
How many pearl danios can be kept together?
Some of the best tank mates for pearl danios are themselves. These peaceful fish are tight schoolers and will swim around the tank, changing direction together.
Though these popular aquarium fish can live in a 10-gallon tank, a larger school will require a bigger footprint; for schooling fish, it’s better to get a more extended tank than a taller tank to allow for extra swimming space.
At least six pearl danios should be kept together at all times. This number will depend on the size of the tank and the stocking list.
Some hobbyists like to intermix danio species together, though this can lead to some problems.
Certain danios have been found to hybridize and create fertile offspring, leading to undesirable traits and even harmful mutations if breeding lineages aren’t tracked.
More importantly, breeding species of danio together can eliminate wild lines of danio. Some wild danio populations have become threatened due to pollution and habitat loss. Those collected specimens can interbreed with other species and end the wild genetic line.
For the most part, all pearl danios available are captive bred, and you don’t need to worry about unwanted interbreeding, though this is something to keep in mind if you plan on mixing species.
Pearl danio behavior
As mentioned before, peal danios are very tight schoolers. They will always stay with their school; if you find that your fish are separating, you may not have enough hiding spots in the tank, or the school may be too small.
Believe it or not, increasing the number of available hiding spots will make your pearl danios feel safer and be more present in the front of the aquarium. A larger school will also help your fish feel most secure.
For the most part, these fish stay at the top of the water column, though they may also venture into the middle portions of the tank. It is unlikely to find them hanging out around the bottom of the tank.
This behavior is primarily due to the pearl danio being an insectivore; these fish love to catch any insects that land on the top of the water, a behavior that can be replicated in the aquarium.
Otherwise, they enjoy fast water currents and will appreciate additional sources of water movement to swim against. They are very eager eaters and will forage for food on floating and submerged aquatic plants.
Pearl danio diet
Pearl danios are insectivores and heavily rely on food at the water surface. In the aquarium, these fish will eat all kinds of food, but it’s best to choose foods that will stay floating.
Pearl danios can be given a high-quality freshwater fish flake or pellet food as part of a balanced diet. Dry flake food is preferred as it stays on the surface longer than sinking pellets.
Their diet may also be supplemented with an assortment of live, freeze-dried, and frozen foods, like mosquito larvae, bloodworms, and frozen brine shrimp. Remember that they have tiny mouths, so some meaty foods may need to be cut up for easier eating.
Because the pearl danio is such an active species, feedings need to be regular. Feed them small portions at least twice a day to keep up with their fast metabolism while preventing unwanted waste and uneaten food.
Breeding pearl danios
Pearl danios are active breeders. It’s not a matter of if they’ll breed but rather when. Like many other egg layers, the pearl danio is an egg scatterer that doesn’t provide parental care for its young.
These freshwater fish will likely breed on their own in mature and stable conditions, but there are some ways to make the spawning process even more successful.
First, make sure to get well-fed and illness-free adult fish. The pearl danios should be alert and have bright colors. As it’s difficult to tell males apart from females, it’s good to get a decent amount of fish to start with, so you’re guaranteed to get a few of both.
To start spawning, feed the fish well and perform several partial water changes with warmer water temperatures–just not so much that you cause your fish to go into shock! This helps mimic seasonal changes and promotes spawning.
Eventually, the females will become round in appearance due to the presence of eggs. At this point, male and female breeding pairs may be moved to a separate breeding tank or left in the main tank.
For both methods, a mesh liner will need to be placed at the bottom of the aquarium to keep the adult fish from eating the eggs.
Once the female has deposited her eggs, the male will fertilize them. After a couple of days, the hungry adult fish may be removed from the aquarium. If breeding these fish in the main aquarium, it’s still recommended to remove the fish to prevent them from eating the eggs and fry.
The eggs will hatch over the next few days, and the fry will become free-swimming. They can be fed baby brine shrimp and other micro foods until they can accept larger foods.
Why is your pearl danio sick?
Though pearl danios are easy to keep, they’re not immune to some of the most common diseases in the aquarium industry.
Unfortunately, many of these small, disposable fish are kept in poor water quality and tank conditions, causing them to arrive at the hobbyist’s home already infected. Many of these diseases can quickly become lethal, killing an entire pearl danio school within a few days.
This can leave many beginner fish hobbyists disheartened and turned off to the hobby as a whole. Luckily, there are many ways to stop your fish from getting sicker or getting sick in the first place before it’s too late.
Quarantine and acclimation
Nobody likes to quarantine fish. We all want to see our new fish in our display aquariums as soon as possible. However, this is a sure way to crash a fish tank, and it’s a lesson you’ll only want to learn once.
Quarantine ensures the health of the display aquarium by providing a buffer from the aquarium store. This process takes about 3-6 weeks, depending on how safe you want to be.
During this time, fish can be observed and treated for diseases; some aquarium hobbyists like to preemptively treat the most common illnesses, while others like to wait for symptoms to appear.
Once quarantine has ended, the fish need to be acclimated. If the water conditions match between the quarantine system and the main display, then acclimation is not required, and the fish can be directly transferred. Otherwise, they will need to be drip acclimated.
Two of the most common illnesses you will come across in danios are ich and dropsy.
Ich is a parasite scientifically known as Ichthyophthirius multifiliis. It is most easily identified by the small white spots it creates on the fish, along with scratching, lethargy, and loss of appetite.
Ich is highly contagious and can quickly become deadly when left untreated. It is introduced into the aquarium through infected fish, aquarium substrate, equipment, or media.
Luckily, ich can be treated with several medications or by raising the water temperature and performing consistent water changes. You should note that some species of ich are immune to this treatment and will need more extensive medications.
Sadly, dropsy is a lot harder to cure than ich, and unfortunately, danios are especially prone to developing it. This disease is diagnosed as an engorged stomach and deformed back. In most cases, dropsy is the symptom of a bigger underlying problem, like a parasitic, fungal, or bacterial infection.
It is believed that dropsy is the direct result of excessive stress from environmental changes, aggressive tank mates, or other health conditions. Treatment for dropsy includes administering antibacterial medications, like Mardel Maracyn 2. However, the underlying cause will also need to be treated for a full recovery.
Dropsy is difficult to diagnose, and recovery is heavily time-dependent; the longer it’s left untreated, the worse the odds are. Luckily, it is pretty avoidable as long as the fish are quarantined and acclimated and the aquarium is checked daily!
Zebra danios are a popular choice for fish keepers just starting out in the hobby due to their easy and forgiving care requirements. But, the pearl danio is just as easy to care for and can offer a different splash of color to the aquarium.
If you have any questions about the pearl danio, other danio species, or have had luck pairing a school of danios with more aggressive tank mates, don’t hesitate to leave a comment below!