Are Rasboras Hardy Fish?

Rasboras fish are hardy due to them having adapted to their natural environment. The natural environment has them living in water sources that sometimes have a pH level of 4.0 or lower with minimal sunlight. As such, they have evolved to safeguard against these conditions. 

This article will detail all there is to know about why Rasboras fish are considered harrier than other fish of similar types. We will explain this by diving deep into how they have learned to adapt and evolve in their natural habitat, making them less susceptible to conditions other fish would succumb to.

Are Rasboras Hardy Fish?

Rasboras are typically one of the hardier fish that you can purchase for your home aquarium. Unlike goldfish or other similar types of fish, a Rasbora can withstand less than optimal conditions.

This is primarily due to two reasons (which we will discuss in detail). They are namely;

  • Having adapted to water with lower pH levels
  • Having adapted to water that does not experience a lot of sunlight

Consider that these two factors regarding “traditional” home aquarium fish will cause serious problems and, in many cases, result in death.

However, Rasboras have been able to adapt to these two elements making them tougher and able to withstand harsher conditions. Let’s look at these two factors in detail.

Harlequin Rasboras in Front of Plants

Why Are Rasboras Fish Hardy?

One of the ways we can determine if a fish species (in this case, Rasboras) is hardy or not is to take a look at their natural environment and how they have evolved to survive in whatever conditions they are subject to.

Depending on the harsh conditions, it would be understandable that fish living in such plight would be better suited over others to withstand adverse circumstances, thus being more “hardy.”.

What Is The Natural Habitat Of A Rasbora Fish?

You would think that you would find Rasbora in brackish water due to them being hardy. Brackish water is a water source (river, stream, lake, etc.) that is considered more “salty” than fresh water but not as much as seawater.

However, Rasboras live and thrive in fresh water. Typically found in South and Southeast Asia along with parts of Southeast China, they originated from Cameroon in Africa.

In terms of specific locations, they will usually be found in floodplains during wet seasons and forest streams.

So why are Rasboras hardy? Because not all freshwater fish are hardy.

We will need to consider the leaves and organic matter found in the water Rasboras are in to understand what makes their constitution so high. The waters and streams Raboras inhabits contain organic matter, dissolved humic acid, and low mineral content.

Understanding Tannins

The reason why Rasboras fish are hardy is due to the tannin-stained rainforest waters they inhabit. Tannins are weak acids that can lower the pH level of water when there is less “buffer” in the system.

Tannins are found widely distributed among many species and plants as they act as a survival mechanism that protects against predictors (which includes pesticides).

The waters in which Rasboras live can sometimes have a pH as low as 4.0 due to Tannins. A low pH is detrimental to a fish’s health and well-being if you have not yet realized it.

How does a low pH Affect Rasboras

It would help if you understood that for “regular” fish, a low pH could cause some serious problems such as;

  • Reducing a fish’s ability to swim
  • Reduces its ability to eat
  • Reduces a fish’s capacity to reproduce
  • Affects a fish’s ability to grow

In situations where a “normal” fish finds itself in an environment with a low pH level, it must do everything it can to survive. In addition to the problems mentioned above, a fish can also become stressed, causing it to become sluggish and sleep more than it usually does.

Now, if we consider that the natural habitat of a Roboras fish sometimes has a pH of 4.0 (or in some cases even lower), it is easy to understand that throughout evolution and being saturated in this type of environment for so long that their physiological structure has adapted.

This is the primary reason why Rasboras fish are so hardy. It means that unlike other species of fish that will succumb to a new environment or ones that tend to change, they will remain steadfast.

Does Sunlight Affect Rasboras?

In general, most species of fish require 8 to 12 hours of light a day. Consider that we touched on what the water and streams are like that a Rasboras inhabits (lives in).

There is a large amount of leaf litter due to these water sources located in forest areas or areas with dense vegetation. These living conditions also resemble that of similar blackwater habitats in South America.

Consider that most other species of fish require a significant amount of sunlight, and if they are not able to get it, then they will experience or become;

  • Lethargic
  • Pale
  • Slow-moving

Eventually, many will even succumb to death. Now, there are fish and other sea creatures that are able to live in complete darkness, but in this case, we are talking about fish kept as pets.

Now, considering that Rasboras are sometimes prone to live in water sources (as stated) filled with large amounts of leafy litter, which could additionally be shaded by thick vegetation (a forest).

Due to this, Rasboras have adapted to a degree to cope without “a lot” of sunlight. This, too, has increased their hardiness, making them less susceptible to harsher conditions where light is inadequate.

Are All Types Of Rasbora Fish Hardy?

There are many various types of Rasbora fish, and now that we know that they are indeed hardy and can withstand quite adverse living conditions, you may want to know if all types are this hardy.

Some types of Rasboras fish are the following:

  • Brilliant Rasbora
  • Phoenix Rasbora
  • Blacklikne Rasbora
  • Chili Rasbora
  • Harlequin Rasbora
  • Clown Rasbora
  • Galaxy Rasbora Dwarf Rasbora
  • Lambchop Rasbora
  • Scissortail Rasbora

It would help to understand that all these Rasbora are prone to the same environment (Southeast Asia and Southeast China).

Even though each may have its own temperament and dietary specifications, they are “engineered” to withstand harsh conditions and waters with low pH levels.

What Else Should I Know About Rasboras Fish

You now know that Rasboras are hardy, which includes all various types because of the environment they are used to.

Thus, if you decide to purchase one (or some) as a pet, you will not need to worry about its survivability if you don’t understand how to test and control pH levels or if the light source provided is inadequate.

You may be wondering then what you should consider and what will affect their health. The main aspect to consider here is their diet.

How Will Diet Affect Rasboras’ Health?

Most Rasboras are considered to be predators and, more specifically, micro-predators. This means that they will typically feed on zooplankton, worms, small insects, and tiny crustaceans in their natural environment.

However, these food sources aren’t always available in captivity, so their dietary needs have to be met in other ways. Thus an adequate replacement is needed.

An adequate replacement for their food is tropical flakes, color flakes, shrimp pellets, and tropical granules. If you have the option to supplement their diet, you should do so with freeze-dried bloodworms or tubifex worms.

Small types of Rasboras will thrive on crushed dried foods to match their mouth size.

Remember not to feed your fish too much as this can raise nitrate and phosphate levels, decreasing water quality and stunting a Rasboras’ growth.


We discovered that Rasboras are quite hardy indeed. This is due to them living and evolving in their natural environment, which sometimes has a drastically low pH level of 4.0 or less. Moreover, most, if not all, types of Rasboras are hardy, with some being more than others.

Additionally, they are also not prone to needing a large amount of sunlight due to their natural environment not providing it in droves.

As such, if you are thinking about a Rasbora as a pet fish, you might be pleasantly surprised at its survival capabilities, especially if you are new to the hobby and are still learning how to adequately deal with water pH levels and lighting conditions in your tank.