Bristlenose Plecostomus are amazing fish, but they are often very misunderstood by beginners as being simple cleaner fish, and they are sometimes paired with goldfish or other coldwater fish.
Is it possible to keep Bristlenose in coldwater? What temperature do Bristlenose need to be kept at? Do they need a heater? And what happens once they are kept outside their normal safe temperature range?
To find out, continue reading;
Can Bristlenose Plecos live in cold water?
Bristlenose are tropical fish, originating in the warm flowing rivers of South America.
They can on occasion live in cool water, as they are adapted to life along fast moving streams, which have a high level of water movement.
These streams are generally quite cool because of this, and have a high level of dissolved oxygen in them.
However, they are not coldwater fish, as this would be to say that they can comfortably withstand temperatures that frequently drop below 15C / 59F, (which they cannot.)
Can Bristlenose Plecos live in a tank without a heater?
It is possible to sometimes keep Bristlenose Plecos without a heater, but we always advise having one, as it saves you a lot of trouble when it comes to preventing disease and promoting top quality care for your fish.
Heating the tank allows you to better mimic the natural environment of the Bristlenose, which results in a happier, healthier fish.
At any given point, there could be a sudden drop in temperature which could shock your fish and make them vulnerable to disease.
It is always better to have a heater, not only as a means of providing the right environment, but also as a preventative measure, in case of any cold spikes during the night which could drop the water temperature very quickly.
How long can Bristlenose Plecos survive without a heater?
Depending on the severity of the temperature difference, Bristlenose may go a few days, to a few weeks, to a few months without a heater.
It is not an easy answer, but typically, we wouldn’t recommend exposing your Bristlenose Pleco to temperatures that are below 20C / 68F for any longer than 48 hours.
It is important that your fish stays warm, as while they can live in cooler water, doing so lowers their immune system and makes them more susceptible to health problems.
Why do Bristlenose Plecos need a heater?
Bristlenose need to be kept in a heated tank because they are true tropical fish, they live in the Amazon Basin, where it stays well above 23C / 73F for the majority of the year.
Bristlenose are used to living in a warm environment like this, and are adapted to life in tropical weather.
When moved to a coldwater environment, they will struggle to function at full capacity, their metabolism will be slow, their immune system will be weak, and they will not digest food properly.
A prolonged exposure to cold water eventually leads to internal health problems in Bristlenose, some of which can be lethal.
It is important to mimic the temperature of their natural environment, so that you can provide the best possible welfare for your Pleco.
What temperature should a Bristlenose Pleco tank be?
Bristlenose are highly adaptable, and are found in a wide range of rivers and estuaries across the Amazon Basin.
However, despite being able to tolerate a wider range of temps than most tropical fish, they still have their limits, and do generally prefer the standard tropical fish temperatures.
From our experience keeping and breeding Bristlenose, we find they are most comfortable anywhere from 23C / 73F to 26C / 79F.
Types of aquarium heaters for Bristlenose Pleco tanks
You may use any type of aquarium heater to keep your Bristlenose tank warm, but sometimes choosing the right tool for the job can be difficult, especially when you don’t have a typical aquarium setup.
For some people, their tank may be too large or have too much water movement to be easily heated using a standard glass heater, so other tools may be in order.
Bristlenose Plecos generally require a large tank, as they are sensitive, territorial fish, who like plenty of space, so a more powerful heater may be in order to keep the larger water volume up to temp.
Titanium heaters are great for this, they work much the same as glass heaters, but have a far greater heat output, and are extremely efficient.
They can be placed either in the tank or in the sump filter, but must be fully submerged and ideally held at a 45 degree angle just like a glass heater.
Some Titanium heaters do not come with a built-in thermostat, so be sure to install one if necessary.
When it comes to choosing the right size, you simply need to correlate the wattage with the literage of the tank, for example, a 300 litre tank would ideally need a 300 watt heater, with some wiggle room of course.
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FAQs about heating Bristlenose Pleco tanks
How do you test the water temperature in a Bristlenose Pleco tank?
Testing the temperature in your Bristlenose tank is easy, there are plenty of tools available on the market for you to use, glass thermometers, tape, digital LCD thermometers, probes etc.
However, not all thermometers are accurate, and choosing the most accurate one can be tricky sometimes.
Different thermometers can be used in different scenarios, but when it comes to picking out some of the best overall, we turn towards digital thermometers, for their ease of use, adaptability, accuracy and clear reading.
Digital thermometers can be implemented into nearly any setup, and will show the temperature of the tank accurately on an easy to read heads up display.
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Do Bristlenose Pleco fry need a heater?
Baby Bristlenose Plecos need to be kept warm if they are to survive and grow into adults.
At a young age they are highly sensitive to fluctuations in temperature and water quality, as they are still at an early developing stage and cannot cope with change as well as their adult counterparts.
Having a heater in a fry tank is very important as it prevents temperature fluctuations from occurring, and ensures that the fry grow properly.
What happens to Bristlenose Plecos if the water is too cold?
Like all fish, Bristlenose Plecos are cold blooded, and rely on their environment to maintain their body temperature.
In order to stay healthy, their body needs to remain within a specific range.
However, once the surrounding water becomes too cold, as a way to preserve energy and stay alive, Bristlenose will begin to slow down their bodily processes.
Their metabolic rate will slow down, and some of their less essential body functions will begin to shut off, conserving energy.
Coldwater fish have the ability to take this further, and can enter torpor or hibernation, where they can live at freezing temperatures for many months.
Bristlenose Plecos however, are not adapted to do this to such an extreme level, and begin to struggle once the surrounding water drops below 16C / 61F.
Below this temperature they will become sluggish, will be unable to properly digest food and will have a weaker immune system.
Eventually their organs will begin to shut down, and if exposed to very cold temperatures for too long, they will perish.
What happens to Bristlenose Plecos if the water is too warm?
On the opposite end of the spectrum, being too hot causes just as much damage.
As the water begins to warm, Bristlenose will become more active, their bodily functions will speed up, they will digest food faster, have a higher metabolism, and they will become more irritable.
If the temperature continues to increase, they will struggle to absorb enough oxygen, and may be seen darting to the surface to swallow air.
If temperatures continue to increase above 32C / 90F, then your Bristlenose will succumb to heat stress, and will eventually die, unless something is done to bring the temperature back down to safe levels.