These are tiny (hand-size) Harlequin Rasboras. They has lots of energy. They are small enough to fit in your hand and have iridescent blue flanks and striking red triangles.
These is active and relatively peaceful fish. Generaly speaking, they are pretty hardy. Keep them content, and they’ll form a tight group, swimming smooth together in a planted tank.
Not meeting their requirements make these fish shy and hiding. Hiding behind wood, they don’t get much color. The biggest thing that makes it work is group size.
Essential Guide To Caring For Harlequin Rasboras
Natural Behavior and Hardy Care
A lot of people keeps them singly, or in a couple in a small tank. Nope. Doesn’t work like that.
They has to be kept in groups. Only with lots of their own kind are they normal and feel safe. Know how many fish to keep so you can take proper care of them.
Minimum School Size for Health
Most people say six or eight. That’s enough to keep them alive. It doesn’t often make them happy.
Six is a crowd. It isn’t a school. Small numbers of fish will pick on one another.
They gets spooked when something disturbs them. They don’t feel secure. Target a minimum of ten fish.
Better yet, fifteen or twenty. The bigger the number, the more naturaly they behave. Instead of seeing individual personalities, you see the school flow.
Tank Size and Shape Requirements
That changes how the tank work. The number of fish determine tank size. A school require more than a 10g tank.
Why? Because it becomes turbulent. Waste accumulates and filter cannot keep up.
Width matter. A 20-gallon long tank is better then a 20-gallon tall tank (cube). Rasboras require horizontal space.
When you confine them in a tight tank, they gets stacked vertically. This cause added stress. Let them stretch out.
Water Quality and Filtration
When they can swims around freely, their colors is better. Group size and water quality. The bigger the group, the more waste.
Big schools requires good filtration. Change the water once a week. Harlequins are sensitive to spikes in ammonia/nitrite.
Sick fish do not make healthy water. Sick fish = dead fish. Dead fish = bad water.
Bad water = sick fish. This is not good. Test water frequently.
Keep settings the same. Harlequins can tolerates a wide range of pH. They do not like pH changes.
Stable 6.8 pH is preferable to fluctuating 7.2 pH. Their mouths are tiny, so you should of feed them carefully. Avoid large flakes, they will sink and disintegrate on contact with the substrate.
Proper Feeding Techniques
The resulting mush make the water dirty. Crushed flakes or micro pellets is better options. Offer small amounts of food twice daily.
In nature, they’re grazing all the time. Feed too much, and water conditions will deteriorate. Anything that reach the substrate is too much.
Scoop up anything left uneaten right away. Doing so will ensure that your tank ecosystem stays intact. Tank mates matter.
Choosing Compatible Tank Mates
No fast fish. No nipping fish (barbs, tetras). Those will takes food and might harass the Rasboras.
Go with mellow bottom dwellers such as cats of the Corydoras genus. Stay out of the Rasboras’ way. Ignore each other.
Tank Setup and Planting
Cover matters. Plants will break up line of sight. Reduce stress.
Floating plants do this. Shade the tank. Rasboras want shade.
The floating plants also offers a ceiling. Having plenty of room, a large school, and mellow tank mates creates balance. Keep the fish healthy to avoid disease.
That will save you work down the road. You have to respect what Harlequin Rasbora are. First, they’re social.
They require a group. Second, provide them with space. Third, buy them in numbers.
Fourth, keep it clean. The reward is an alive-looking tank. You’ll see blues and reds dancing on the glass.
Not out of fear but out of pure, unadulterated joy.
