Harlequin Rasbora
The Harlequin Rasbora (Trigonostigma heteromorpha) is a small, freshwater fish. They have a beautiful metallic color and are resilient and easy to care for in a fish tank. Harlequin Rasboras are found in the wild in Asia in countries such as Malaysia and Thailand. They prefer dimly lit rivers and streams with slow moving waters – much in the same way that Neon Tetras do in South America.
The Harlequin Rasbora is part of the Cyprinidae family. The life expectancy of a Harlequin Rasbora is around 6 years but they can live up to 8 years in the right conditions. A mature Harlequin Rasbora grows up to two inches (5 cm) long.
Harlequin Rasboras have a copper / orange body with a distinct black patch which is roughly triangular in shape. Males have a slightly larger black patch with the bottom being more rounded than is evident in females.
They are a striking fish which, when added as part of a group, will add a vibrant splash of color to your tank.
Harlequin Rasboras are often called Red Rasboras or even Lamb Chop Rasboras (due to the shape of the black patch on their side).
Caring for your Harlequin Rasbora
The Harlequin Rasbora can make for a great aquarium fish, and requires only a low to medium amount of care. They do, however, need at least a 10 gallon fish tank – especially if you are going to keep them in a shoal. Although 10 gallon fish tanks are great, it is worth considering a 20 gallon, or even a 50 gallon fish tank as these will allow you to keep more fish in a healthy environment.
Habitat
Harlequin Rasboras are native to Asia and are found in Malaysia, Singapore, Sumatra and Thailand. They are most at home in waters similar to those of the Neon Tetras in South America That is, slow moving rivers, streams and peat swamps that are darkened by decaying organic matter and contains high levels of humic acids.
These environments are also characterized by tropically warm water and have neutral or lightly acidic waters.
Fish Tank Conditions
As always, it is sensible to provide Harlequin Rasboras with a similar environment within your fish tank that they would experience in the wild (within reason).
The tank should ideally contained live plants that are native to the Rasboras’ home environment. These plants species could include Cryptocoryne, which does well in low lighting levels. The Rasboras will welcome the hiding areas created by these plants, but don’t overdo it – they still need plenty of water to swim freely in. Not only is this best for them, but you will also be able to enjoy the sight of them moving in full flow.
Ideal Water Conditions
Harlequin Rasboras thrive in water conditions similar to their natural habitat. The water should be soft, clean and either neutral or slightly acidic. There is some debate as to the optimal temperature range, but the Harlequins will certainly be happy within the 72-82 degrees Fahrenheit range (22-28 degrees centigrade). 28 degrees centigrade is both their upper limit, and the temperature at which they usually breed.
A pH range of 6.0-7.5 works well, combined with a hardness of less than 12dH.
Lighting
Harlequin Rasboras have no specific lighting requirements. Most standard aquarium lights will work well for your home aquarium. They will, however, need a heater to ensure that the water temperatures are appropriate.
Filters
The natural habitat of the Harlequins has slow moving waters. There is therefore no need (or indeed desire) for your filter to exert excess current in the water. Look for a filter that is strong enough to provide sufficient filtration in your tank, but ensure that it is not overpowering.
Feeding / Nutrition
Harlequin Rasboras are omnivores and can be fed a wide range of foods. It is best to vary their diet to ensure that they obtain all of the required nutrients. Using flakes as a core component and then introducing occasional freeze-dried bloodworms and Daphnia works well. Mosquito larvae are a great option if you can source them.
Be careful to ensure that you only feed them small pieces to ensure that they do not choke.
Only feed Harlequin Rasboras as much as they can eat in 2-3 minutes should help you to regulate their food volumes. Stop adding food if they stop eating it immediately (don’t allow food to wallow in the tank).
Difficulty
Harlequin Rasboras are easy to care for and make for great fish for beginners. As with many other smaller fish, as long as they are fed a good diet, the tank is kept clean and the water type is correct they will likely thrive in your aquarium.
Harlequin Rasbora Behavior
Harlequin Rasboras are sociable fish that live in large groups in the wild. For this reason, it is best to ensure that you have a large enough fish tank to enable you to keep a group of at least 6 (and ideally 15+) of these fish in one tank. Harlequin Rasboras begin to get nervous and anxious if they are kept in small groups and will take up hiding positions within the aquarium.
Within tanks they will spend the majority of their time at the middle to top height level of the tank. It is possible to add them to a community aquarium, particularly if their other inhabitants mainly occupy the bottom of the tank. Especially when comfortable, and in large groups, Harlequin Rasboras can make for fascinating and impressive visual displays within your tank.
It is best to keep them with other non-aggressive fish – consider Neon Tetras, Dwarf Gouramis and Corys. Avoid putting them with aggressive fish such as Angelfish and Cichlids – you may wake up to less Harlequin Rasboras than you started with!
Harlequin Rasbora Breeding
Ideal Breeding Conditions
The temperature in the breeding tank (or main tank if breeding there) is particularly important and should be kept at a constant 82 degrees Fahrenheit (28 degrees Centigrade). The water should also be soft, very lightly acidic and quite dim.
Breeding Process
Many Rasboras are egg scatters. The Harlequin Rasbora, however, approaches breeding in a different way, actively sticking their eggs to the underside of leaves in the aquarium.
The female will swim in an upside down position, along the underside of a leaf. Once she is joined by a male she will eject her eggs which will then stick to the underside of the leaf. At this point they will be fertilized by the male Harlequin Rasbora. This process will continue, with approx. 10 eggs being ejected and fertilized each time, until around 100 eggs have been fertilized.
Once complete the parents should be removed from the tank (otherwise they may eat their young). The eggs will hatch approximately 24 hours later. Appropriate food can include:
- Infusoria
- Shrimp Brine
- Commercially available egg layer foods
Harlequin Rasbora – Diseases
Harlequin Rasboras are not disease prone and are known to be hardy fish.
Like many fish, however, they will struggle if the water is not kept clean. Poor quality water could result in common diseases such as Ich and fin rot. With proper care, however, it should be possible to keep your Harlequin Rasboras disease free.
Harlequin Rasbora – Conclusion
Harlequin Rasboras can make for great aquarium fish. Their colors and tendency to swim as a school can create some brilliant visual displays. Added to this their peaceful and non-aggressive nature it is easy to see why many fish keepers enjoy having them in their aquarium.
It is possible to find Harlequins in most good pet shops due to their popularity. Although they are easy to keep, breeding is significantly more difficult. It can, however, be very rewarding if you want to try!
If you end up deciding that Harlequin Rasbora is not for you, there are still a range of different options available to you. Fish such as the standard Neon Tetra or even Tiger Barbs could make great alternatives for your tank!