Why Are My Rosy Barbs Dying (and how to save them)?

Affiliate Disclaimer:

FishKeepingAnswers.com is reader-supported. When you buy through links on our site we may earn a commission.

Rosy Barbs are one of my favorite fish. They are seriously underappreciated in the hobby. I am not sure why more local fish stores do not sell them. When mature, the males have the most intense red coloration and the females sport a wonderful rose gold color.

These fish are generally considered hardy, but when they start dying it can be incredibly frustrating. In this article, I will try to draw on my 30+ years of experience in fish keeping to help work out why your Rosy Barbs are dying, and how you can save them.

Why Are My Rosy Barbs Dying

I have been keeping and breeding Rosy Barbs for many years. In fact, Rosy Barbs were the first member of the Barb family I ever bred, along with a group of Tiger Barbs. Unless you have kept them, I don’t think you can appreciate the intense color the males get when in spawning mode.

There are essentially 3 main reasons Rosy Barbs die unexpectedly. These are poor water quality, low oxygen levels, and disease. Rosy Barbs can also die suddenly when their water temperature drops too low or becomes too high.

Below I have listed the 10 reasons that, in my experience, can cause the death of Rosy Barbs. I look into each one individually and offer a solution to the issue so you can hopefully prevent any more Rosy Barbs, or other fish in the aquarium, from dying.

  • Poor Water Quality
  • Disease
  • Low Oxygen Levels
  • Overstocking
  • Water Temperature
  • Stress
  • Ammonia Spike
  • Overfeeding
  • Poor Quality Diet
  • Aquarium Cycling Issues

Poor Water Quality

Poor water quality is one of the biggest killers of fish in our hobby. The problem with water quality is you can’t judge it just by looking into the tank. An aquarium can have crystal clear water, but the quality of that water can still be poor.

When we say the water quality is poor, we are generally referring to the levels of ammonia, nitrite, and nitrate present in the water.

When our fish go to the bathroom, their waste is high in ammonia, and ammonia is highly toxic to fish. Fortunately, there are naturally occurring bacteria that live in our fish tanks (and are present in high numbers in our filters). These bacteria turn the highly toxic ammonia in to the slightly less toxic nitrite.

Although nitrite is less toxic than ammonia, it can still kill our fish pretty quickly. There is another strain of bacteria that naturally inhabits our aquariums, and these bacteria convert nitrite, into the less toxic still nitrate.

Most of the fish we keep, including Rosy Barbs, can handle a certain amount of nitrate in their water. The number 40ppm (parts per million) is often banded around, but many fish can tolerate numbers well above that. In my own tanks, I don’t tend to worry about the majority of my fish until the level of nitrates reaches around 100ppm.

To remove, or at least lower the levels of nitrates, we need to grow live aquarium plants. Live aquarium plants absorb nitrates. Also, carrying out partial water changes on a regular basis will reduce the level of nitrates.

How Do You Know Your Aquarium Water Quality Is Poor?

As mentioned above, you can not tell the quality of your aquarium water just by looking at it. Neither ammonia, nitrite nor nitrate has any color to them. Crystal clear water can be very poor chemically.

The only way we can judge the quality of our water is by using an aquarium test kit. Test kits give us an almost instant result, allowing us to take the appropriate action.

There are two ways we can test our aquarium water, either with a liquid test kit or by using test strips. I have spent some time reviewing which aquarium tests are the best, and you can find out more in this article titled Best Aquarium Test Kits (tried and tested).

Most test strips and liquid test kits will test for pH, ammonia, nitrite, nitrate, and chlorine, and many will test even more parameters.

Test strips are quicker to use than liquid test kits. Test strips will often give you a result within around 60 seconds, whereas liquid test kits can take 5 minutes or more. However, in my experience, liquid test kits do tend to be more accurate.

API FRESHWATER MASTER TEST KIT 800-Test Freshwater Aquarium Water Master Test Kit, White, Single, Multi-colored
  • Contains one (1) API FRESHWATER MASTER TEST KIT 800-Test Freshwater Aquarium Water Master Test Kit, including 7 bottles of testing solutions, 1 color card and 4 tubes with cap
  • Helps monitor water quality and prevent invisible water problems that can be harmful to fish and cause fish loss
  • Accurately monitors 5 most vital water parameters levels in freshwater aquariums: pH, high range pH, ammonia, nitrite, nitrate
  • Designed for use in freshwater aquariums only
  • Use for weekly monitoring and when water or fish problems appear

Last update on 2024-07-19 / Affiliate links / Images from Amazon Product Advertising API

How to fix poor water quality

If you test your aquarium water and discover the quality is less desirable than you had hoped, taking immediate action can prevent further fish from dying.

The best way to fix poor water quality is to carry out an immediate particle water change. When I find one of my tanks has poor water quality I typically carry out a 25% to 50% water change, replacing the existing tank water with fresh, dechlorinated tap water. I will usually then re-test the water after 4 or 5 days, and repeat the large water change if necessary.

Acting quickly will reduce the number of fish that die due to poor water quality.

Pests & Disease

Another common reason we lose fish is due to pests and diseases. Pests and diseases are often introduced to our aquariums when we add new fish. Many diseases are easily passed from fish to fish, meaning when we introduce a fish carrying a pests or disease, they usually spread quickly throughout our aquarium.

If you are concerned your Rosy Barbs may be dying due to pests or disease, early identification of the problem is essential.

In my experience, the most common pests and diseases we see in our aquariums are;

Although there are many other pests and diseases our Rosy Barb can suffer from, I have found these 4 to be the most common. Identification and early treatment are essential to prevent further Rosy Barbs from dying.

Low Oxygen Levels

Many people do not realize, that even though fish live underwater, they still need to breathe oxygen. Fish use their gills to extract oxygen directly from the water. They essentially take in oxygen and give out carbon dioxide, much like us.

Occasionally, oxygen levels in the water can drop so low that the Rosy Barbs struggle to breathe.

This is often characterized by them ‘gasping’ at the water surface. It is thought by some they do this to try and grab oxygen from the air above. In fact, it is just the case that the highest concentration of oxygen can be found in the water nearest the surface.

As is so often the case, the best way to solve low oxygen concentrations is to carry out a large partial water change. Changing around 25% to 50% of the water in the aquarium will bring in lots of oxygen-rich water, increasing the amount of dissolved oxygen available for the Rosy Barbs.

In the long run, the best solution to low oxygen levels is two-fold. Firstly, adding live aquarium plants will increase the amount of oxygen available to the fish. Just like plants on land, aquatic plants take in carbon dioxide from the water and give out oxygen, increasing the amount of oxygen available in the water for the fish.

Secondly, adding an airstone connected to an aquarium air pump will raise the oxygen levels. As the bubbles rise from the air stone, they agitate the water surface. This water movement allows an exchange of carbon dioxide in the water for oxygen in the air above. This is why fast-moving rivers typically have more dissolved oxygen in the water than slow or non-moving ponds.

In my own fish room, almost every single tank has an airstone bubbling away no matter what fish are living in the tank.


I think there is one mistake that all fish keepers, including myself, make and that is overstocking our aquariums. In nature, there would never be the same ratio of fish to the water volume as we keep in our aquariums.

Overstocking can lead to poor water quality and low oxygen levels in the water.

The only way to solve overstocking is to reduce the number of fish you keep or upgrade to a larger aquarium. Sometimes upgrading to a larger filter can also help.

Water Temperature

Rosy Barbs are incredibly hardy fish, and they are often recommended for new fish keepers. The problem is, that they actually do not require their water to be as warm as many other tropical fish in the hobby. Most tropical fish want their water to be somewhere between 72°F and 78°F (22°C and 25.5°C) whereas Rosy Barbs want their aquarium water to be between 64°F and 72°F (18°C and 22°C).

When we keep Rosy Barbs in water that is too warm (and also if it is too cold), the Rosy Barbs can become stressed, and a fish that is stressed is more susceptible to pests and diseases.

Fitting a good quality digital thermometer to the front of our aquariums is the best way to monitor the temperature of the aquarium. If you discover the water in your Rosy Barb aquarium is too warm, try turning down the heater. Do however be mindful of the other fish you have in the aquarium as they may suffer if the water temperature is too low for them.


Fish keepers often underestimate the effect stress can have on our fish. Stress can kill fish very quickly or can make them more susceptible to pests and diseases.

Almost every item on my list above will cause your Rosy Barbs to be stressed. If the water is too warm, if the water quality is poor, if the Rosy Barbs are living with boisterous tank mates, the list goes on.

External factors such as the tank being situated next to a loud TV or a child banging constantly on the glass can cause Rosy Barbs to be stressed.

There is no easy way to tell what might be causing your Rosy Barbs stress, it is more a case of looking at the tank and trying to see what might be causing the problem.

Ammonia Spike

As mentioned above, when our fish go to the bathroom, their waste is high in ammonia. Even in small quantities ammonia can be toxic to fish, burning their gills as they try to breathe.

It is the job of our filters, or rather the bacteria living in those filters, to convert that ammonia first to the less toxic nitrite, then the less toxic still nitrate. Our filters usually do this job really well, but sometimes things go wrong.

An ammonia spike is exactly that, a spike in the amount of ammonia present in the aquarium water.

The most common cause of an ammonia spike is overfeeding our fish (see more on overfeeding below). If a fish dies, and we don’t remove the body, the dead fish will release ammonia into the water as it decays.

Sometimes an ammonia spike can be caused by a power failure. If the power goes out for a couple of hours, the filters will stop running. Without the water running through the filter, the beneficial bacteria living in that filter will die. When the power comes back on, there will essentially be little to no beneficial bacteria alive in the filter, meaning there is no way for your filter to process the ammonia in the fish’s waste. This can lead to an ammonia spike.

The best way to deal with an ammonia spike is to carry out a large partial water change. Changing 50% to 75% of the water will reduce the amount of ammonia in the water by 50% to 75%, which will make a big difference to the fish.

It can take several days for the number of bacteria to increase to sufficient levels, so you may have to repeat that water change several times over the coming days.


To me, feeding my fish is the best part of my hobby. I am a self-confessed fish food hoarder. I probably have 30 or 40 different types of fish food in my fish room.

When it comes to feeding, what many of us do is add a large pinch of food once a day. By feeding this way, a lot of the food will sink to the bottom of the tank, landing behind decorations or in clumps of plants. This uneaten food then sits and rots, releasing ammonia into the water column.

Overfeeding is even more of a problem when we go on vacation and ask friends or neighbors to feed our fish for us. Non-fishkeepers always add too much food to the tank. They look at the amount you asked them to put in and think to themselves that isn’t enough. Fish are most frequently overfed during family vacations.

The best way to prevent overfeeding is to feed your Rosy Barbs 2 or 3 small meals a day rather than one large meal. Only ever add about as much food as the fish can eat within 2 or 3 minutes.

Poor Quality Diet

As well as overfeeding, Rosy Barbs can die if they are fed a poor quality diet for a long period of time. To be healthy, Rosy Barbs need a balanced diet that has a variety of vitamins and mineral in it. We should always try to feed our fish the best quality food we can.

Poor quality, typically cheap food, is full of fillers. Fillers are cheap ingredients that bulk out the food, helping keep the costs down. However, fillers offer our fish nothing nutritionally.

When I give fish talks around the country, I usually recommend fish are fed either Bug Bites, which are made by Fluval, or Vibrbites from Hikari. Both these foods are made from high-quality ingredients, with Black Soldier Fly Larvae being the number one ingredient in the Bug Bites.

Hikari Vibra Bites, fish flavor (9.8oz), Red
  • Carefully selected color enhancing ingredients help rapidly bring out the brilliant colors of your fish
  • Uniquely balanced formulation offers nutrition live worms cannot without the parasite or bacteria risks.
  • Inclusion of mealworms make this a delicious offering most tropical fish immediately attack
  • Unique stick that readily moves through the water column like live food
  • Ideal tropical fish who prefer live foods

Last update on 2024-07-19 / Affiliate links / Images from Amazon Product Advertising API

Aquarium Cycling Issues

If your Rosy Barbs are dying shortly after being added to a new aquarium, it may be due to cycling issues. When we first start a new aquarium, it takes time for the beneficial bacteria that process the fish waste to form in sufficient numbers. This process is called cycling the aquarium.

Sometimes, if we add our fish too quickly, the amount of waste produced by the fish outweighs the amount of waste the bacteria can process. This can cause our Rosy Barbs to die.

Once again, the solution to Rosy Barbs dying because of cycling issues is carrying out a water change. A water change will reduce the ammonia and nitrite in the water, making the aquarium safer for the fish until the filter bacteria can increase in number.

How to Keep Your Rosy Barbs Healthy

So above we have looked at some of the reasons our Rosy Barbs might be dying, below I go through some of the things we can all do to keep our Rosy Barbs Healthy.

  • Regular water changes
  • Maintaining the aquarium
  • Disease prevention and treatment
  • Feeding a balanced diet

Regular water changes

As discussed above, fish have no choice other than to live in the water we provide them. They don’t have an opportunity to swim away if the water quality drops.

Carrying out regular partial water changes is the single biggest thing we can do to keep our Rosy Barbs healthy. In my experience, a weekly 25% water change will do wonders for your aquarium. Water changes reduce nitrate levels, remove contaminants from the water and allow us to siphon out uneaten food, fish poop, and other debris that may be laying on the substrate breaking down.

Regular water changes allow us to eliminate an issue before it becomes a problem

Maintaining the aquarium

Along with regular water changes, keeping up with your general aquarium maintenance will go a long way to stopping your Rosy Barbs from dying. Cleaning your filters, vacuuming the gravel, and trimming plants are all jobs that help keep an aquarium system running and your fish thriving.

Disease prevention and treatment

Disease prevention is always better than cure. Before adding any new fish to your aquarium, consider quarantining your new fish in a separate aquarium for at least one week before moving them into your main display tank.

Quarantining new fish gives us a chance to spot if they are suffering from any pests or diseases before we mix them with our healthy fish.

Feeding a balanced diet

Rosy Barbs are omnivores. They need a wide variety of foods. For the biggest, strongest, healthiest fish, you need to feed them a balanced diet.

A good mix of dried foods, live foods, and frozen foods will help give your Rosy Barbs all the vitamins and minerals they need to be active and colorful.

In Conclusion

Rosy Barbs are essentially hardy fish that should live for around 4 to 6 years in an aquarium. It can be distressing when they appear to be dying for no reason. Taking the time to work through the list above may help solve the reason why they are dying.

For further reading why not check out my article Most Common Tropical Fish Pests & Diseases (with solutions!)

About the Author

I’ve been keeping, breeding, and showing tropical fish for nearly 30 years. Over that time I’ve done it all! I’ve had great success and I’ve made some really foolish mistakes (like the time I bought an Asain Walking Catfish). Read more…
Richard James

Article Sources: