Do Harlequin rasboras lay eggs?

In this post, we will answer the question “Do harlequin rasbora lay eggs?”. We will also discuss how to breed harlequin rasboras in captivity.

Do Harlequin rasboras lay eggs?

Yes, harlequin rasboras do lay eggs. Rasboras are not livebearers, hence they are not officially pregnant at any point in their lives. A fish that is gravid, rather than pregnant, is defined as one that is carrying eggs. 

While many other species of rasboras are egg scatterers, harlequin rasboras are egg layers, meaning they lay all of their eggs in one location, as opposed to many other types of rasboras that are egg scatterers, meaning they scatter their eggs all over the tank. 

How to detect if a harlequin rasbora is going to lay eggs? 

The question then becomes how do you determine whether your Rasbora is pregnant or bloated? The following are the primary indicators of a pregnant Rasbora: 

• Eating more than normal. 

• Increased body size, with eggs visible. 

• Behaving in a manner that differs from the norm. 

• In your Rasbora school, you have both males and females enrolled. 

Rasboras are egg layers, which means that they are never genuinely pregnant because the fish fry embryos develop inside the eggs rather than in the body of the female rasbora. Rasboras are also known as rasboras. 

What is the breeding process for harlequin rasboras? 

Rasboras are one of the more difficult fish to breed at home, primarily because they demand very specific environmental conditions. 

For starters, if you intend to breed these fish, you will almost certainly want to build up a mating tank for them to use. 

This is because you will need to supply your rasboras with plenty of space to reproduce as well as specific environmental conditions. 

Meeting the Breeding Requirements for Rasbora 

First and foremost, the water must be extremely soft in terms of water hardness, and it must also be slightly acidic, with a pH of less than 7, preferably closer to 6.0 on the pH scale. 

To encourage rasbora mating, the water temperature should be kept consistent at 82.5 degrees Fahrenheit, which is a little warmer than the species’ normal preferred temperature. 

After that, you will want to incorporate a great number of attractive live plants with large leaves into the arrangement. Because breeding is always a competition between men, make sure that for every female in the breeding tank, you have at least two males present, as they will compete for the privilege to spawn alongside the female. 

Additionally, you should add some water filtration to the breeding tank, albeit you should keep the flow rate moderate to avoid excessive water movement. 

Rasboras require excellent nutrition when they are reproducing, and this is especially true for females. Provide them with an appropriate mixture of life and freeze-dried foods to help them fill out a little bit and provide them with the energy they require. 

When Is It Time To Breed? 

As soon as all of these criteria are met, the female rasbora will position herself vertically in the water with her face pointed downward, and she will do so next to a huge leaf to protect herself from predators. 

The males may then compete for the privilege to spawn, and once they have figured it out, the winning male will approach the female and attempt to mate with her. The female will position herself such that she is upside down and her belly is exposed to the leaf. 

She will release her eggs while the male is in the process of fertilizing them. These eggs have a natural adhesive on the underside of the leaf, which will allow them to adhere to it. This is how rasboras reproduce, and as you can see, it is a quite basic and quick mating rite that doesn’t require any particular skills or equipment. 

What Is the Appearance of Rasbora Eggs? 

Rasbora eggs are very little, measuring just a few millimetres in diameter, completely spherical, resembling a very small green pea, and partially white and translucent in colour. 

It is because they have a natural adhesive on them that they will usually stay together in bunches and adhere to other surfaces such as leaves and rocks. 

How Long Does It Take For Rasbora Eggs To Hatch? 

Given that the water temperature is around 82 degrees Fahrenheit and that the eggs have been laid and fertilized by the males, healthy rasbora eggs should hatch between 17 and 19 hours after being laid.


In this post, we answered the question “Do harlequin rasbora lay eggs?”. We also discussed how to breed harlequin rasboras in captivity.

If you have any thoughts or doubts, feel free to drop us in a comment below!

Frequently Asked Questions (FAQs): Do harlequin rasboras lay eggs?

Are Harlequin rasboras aggressive?

Each time they nip at one another, it is only a small nip and it does not happen very often. They will never be hostile towards other fish until provoked.

Are harlequin rasboras easy to breed?

It is well known that harlequin rasboras are notoriously difficult to reproduce in home aquariums, primarily due to the fact that they have extremely strict water requirements. To have any chance of reproducing, they must be kept in soft, acidic water at a temperature of 82 degrees Fahrenheit.

How many eggs does a Harlequin rasbora lay?

Typically, a healthy pair will have deposited between 25 and 100 eggs. Rasboras are not keen egg eaters, but they will occasionally consume a few of the eggs if they are available. Because of this, it is recommended that the parents be removed as soon as possible once the breeding cycle has concluded. It takes around 24 hours for the fry to hatch, and they are free-swimming by the third day.

Do harlequin rasboras eat their babies?

When breeding in tanks, it is critical to remove the adults as soon as the spawning process is complete to avoid contamination. They will consume the fry or juvenile fish if they are not protected from predators. The eggs of the harlequin rasbora hatch in around 24 hours.

Where do harlequin rasboras lay eggs?

Unlike other rasboras, which lay their eggs on the underside of the leaves of plants such as Cryptocoryne and Aponogeton, the harlequin rasbora lays its eggs on the underside of the leaves of plants such as Cryptocoryne and Aponogeton.

Do rasboras breed in captivity?

If you are starting from scratch in captivity, begin with a dark, sandy, or gravely substrate and add some leafy debris on top. Harlequin rasboras have been reported to reproduce and raise their young in a well-planted aquarium with other gentle community fish with little or no aid from the aquarist if the tank is properly planted.


Stanton, L. 2022. Is My Rasbora Pregnant or Bloated? How to tell the difference.

Breeding rasboras.

Kottelat, M. and K.E. Witte, 1999. Two new Microrasbora species from Thailand and Myanmar, with two new generic names for Southeast Asian small cyprinid fish (Teleostei: Cyprinidae). J. South Asian Nat. Hist.

Lim, K.K.P. and P.K.L. Ng, 1990. Singapore’s freshwater fish. Singapore Science Centre, Singapore.

Monkolprasit, S., S. Sontirat, S. Vimollohakarn and T. Songsirikul, 1997. Checklist of Fishes in Thailand. Office of Environmental Policy and Planning, Bangkok, Thailand.