When it comes to popular schooling fish, popular ones are the speedy Zeebra Danios, the colorful Neon Tetra or Cardinal Tetras but another schooling fish that I want to recommend is the Harlequin Rasbora (Trigonostigma Heteromorpha).
This small fish is part of the Cyprindae family (which includes carps, true minnows and more) and Trigonostigma genus.
They were first introduced to aquarists back in the early 1900s and the Rasboras from Southeast Asia were quite popular. Of course, there are many types of Rasboras but the Harlequin Rasboras is a small fish which many people want to see in their tanks.
For one, they are small but their bodies are slightly larger than a Neon Tetra. They are also an interesting schooling fish that tend to follow each other, occasionally you’ll notice one or two wanting to become adventurous on its own but quickly rejoining the pack.
The “Harlequin” name was given because of its black triangular patch on the body (as it was reminiscent of a harlequin costume).
They have this orangish-pink color towards the tail area, but there is another fish that looks almost exactly like it, the Lambchop Rasbora (false harlequin Rasbora – Trigonostigma espei). Lambchops are more slender and have a similar but slightly different pattern in the black mark and you can find it towards the dorsal fin.
These fish only grow up to two inches and personally, I’ve never seen a two inch Harlequin Rasbora.
As for the distinction of male or female, males have a slightly larger black body patch than females and more red coloring in the dorsal and caudal fins. They also have a more rounded anal fin.
As for breeding them, well…you’ll have to keep watch on these fish because the parents will attempt to eat the fry as soon as they hatch. They are also different from other rasboras as they don’t scatter their eggs, they actually put their egs under leaves of plants (esp. Cryptocoryne). She’ll swim under the leaf and attach her eggs. The male will swim around the body of the female and will fertilize the eggs for several hours and can produce up to a 100 eggs (I’ve read there could be much more). Fertilized eggs wil take 18 hours to hatch and prefer temperatures of 82.4F (28 C) and will need to be given fine sizes of food for two weeks.
If you are going to keep this is a community tank, I do recommend keeping them in a group of six. In addition, if you are feeding and they are living in a community tank with other types of fish, because the Harlequin Rasboras tend to avoid conflict, I would feed one side for your larger fish and then one side for the Harlequin Rasboras.
One thing that I notice about Harlequin Rasboras, they like to stay towards the top, rarely in the middle, never at the bottom.
Their lifespan is around five to eight years and prefer live plants.
Again, these are schooling fish but if you want schooling fish that rapidly swim around tank, then I recommend Danios. If you want schooling fish that are similar but as opposed to swimming up top and more towards the bottom, I recommend Neon Tetras (especially in terms of colors and a smaller size).
But overall, Harlequin Rasboras are easy to keep, fun to have in the community tank and definitely worth considering if you want to own schooling fish.
