Best Cold Water Aquarium Fish

Are you looking for a cost-effective way to enjoy the beauty of an aquarium without the added expense of a heater? Consider cold water fish!

This article explores the best species for your aquarium, from beginner to expert. We’ll provide care requirements, temperature ranges, and maintenance tips to ensure your aquatic pets are healthy and happy. Plus, we’ll discuss the benefits of keeping cold water fish and how to care for them best.

Whether you’re a seasoned aquarium enthusiast or a beginner, this guide will help you create a beautiful, functional, thriving cold-water aquarium.

Key Takeaways

  • Many cold-water fish species can live without a heater, offering cost savings and a natural tank environment.
  • This list includes species with care requirements and temperature ranges, ranging from 5 to 55-gallon tank sizes depending on the species.
  • Some cold water fish require intermediate to expert-level care, while others are great for beginners.

Endler’s Livebearer


Poecilia Wingei is a tiny version of the guppy but has a twist. This little fishy has been bred to flaunt colorful colors and unique fin shapes.

The original wild-type Endler’s livebearer is just as amazing as nails, able to thrive at room temperature and handle a pH range of 6.5 to 8.5. They’re also incredibly friendly and can get along with many other fish.

Regarding their water temperature, they’re okay with anything between 64°F and 82°F.

If you’re looking to breed Endler’s livebearers, it’s as easy as pie. Just prepare a 10-gallon tank and add around two male and four female fish. Fill the aquarium with lush live plants and provide plenty of hiding spots. Before you know it, your tank will overflow with adorable little fish babies! Endler’s livebearers are incredibly fertile creatures and will breed like rabbits in a planted tank with many covers.

So there you have it! Whether you opt for the showy Poecilia Wingei or the hardy Endler’s livebearer, you’re in for a treat. These little fish will bring life and joy to any aquarium they call home.

Celestial Pearl Danio (Galaxy Rasbora)


Are you looking for a unique addition to your tank? Check out the Galaxy Rasbora, also known as Celestichthys margaritatus. This stunning member of the Danio family boasts dramatic spotted coloration that you won’t take your eyes off.

While they may be timid, this peaceful nano fish does well in community tanks. Do not house them with highly active or larger fish species to keep them happy.

With an adult size of just 0.75 inches, the Galaxy Rasbora is a great choice for smaller tanks. Keep their water temperature between 68–78 °F and ensure a minimum tank size of 10 gallons. With a moderate difficulty level, these fish are perfect for hobbyists looking for a bit of a challenge.

Two Spot Barb


The Two Spot Barb, scientifically known as Puntius bimaculatus, is an easy-to-care-for cold water fish species that can add color to your aquarium. These fish are native to Southeast Asia and are typically found in slow-moving rivers and streams. They have a vibrant orange-red body with two black spots on their sides, which make them stand out in any aquarium.

Two Spot Barbs are omnivorous and eat flakes, pellets, and live or frozen foods. They are not picky eaters and will readily accept any food. They are prolific breeders and can lay up to 500 eggs at a time. To encourage breeding, provide hiding places and vegetation in the tank.

A minimum tank size of 20 gallons is suitable for a small group of Two Spot Barbs.

Paradise Fish


If you’re looking for a visually-pleasing species to add to your aquarium, the Paradise Fish is a perfect choice. These fish have been captivating aquarists for years with their stunning colors and flowing tails.

Don’t be intimidated by caring for these fish, as anyone can do it! You just need to take the time to understand their basic care requirements and set up their habitat properly. Once you have that down, you’re good to go.

Be aware that Paradise Fish can be a bit aggressive in certain situations or with certain tank mates. But, this is easy to avoid by keeping them with peaceful fish that are too large to be bothered.

These fish typically grow to around 2.5 inches, making them an excellent choice for beginners or intermediate aquarists. Just ensure you have a tank that’s at least 20 gallons and keep the water temperature between 68°F and 82°F. Your Paradise Fish will thrive in their new home with some care and attention.

Rosy Barb


These beautiful cold-water fish have large, reflective scales with gorgeous variants. While they may not be the best choice for a planted setup due to their leaf-chewing tendencies, they are easy to care for and look stunning in a group.

Long fins and neon varieties are available for those looking to add a mixture to their tank. Rosy Barbs are social fish and thrive in larger groups of at least 10 or more. If you have an unheated tank, you’ll be happy to know that these fish do well in temperatures between 60-75 °F.

Here’s a quick look at the Rosy Barb: their scientific name is Pethia conchonius, and they typically reach a size of around 3 inches. They’re easy fish to care for, making them a great choice for beginners. Ensure you have a minimum tank size of 30 gallons to keep them happy and healthy!

Gold Barb


This popular fish is an excellent choice for any tank with its vibrant yellow color and hardy nature. Plus, it’s super easygoing and gets along great with other species.

Remember that Gold Barbs do best in schools, so you’ll need a decent-sized tank to accommodate them. And if you’re looking to add one to your collection, be prepared to put in a little effort – they can be tricky to find due to high demand.

They grow to be around 3 inches, are easy for beginners to care for, and require a minimum tank size of 20 gallons. Keep their water temperature at 64°F to 75°F for optimal health.

But trust us, and it’s worth the search! These fish are a beginner-friendly option that can add color and personality to any aquarium.

Bloodfin Tetra


Get ready to add color to your unheated aquarium with the Bloodfin Tetra. These flashy fish have silver bodies and deep red fins, which they move in schools to create a stunning visual display. Not only are they easy to care for, but they’re also hardy and can handle fluctuations in temperature, making them ideal for varying climates.

These fish can live up to five years or more, so plan for at least six to keep them happy. However, remember that they tend to nip at fins, so be careful when choosing other fish to add to your tank.

Here are some quick facts about the Bloodfin Tetra: their scientific name is Aphyocharax anisitsi, they can grow up to 2 inches, they’re easy to care for, and they require a minimum tank size of 20 gallons. Keep their water temperature between 64-82°F, and you’ll have a colorful addition to your aquarium that’s sure to impress.

Sunset Variatus Platy


Livebearers hold a special place in our hearts because of their adorable baby fish, and the sunset variatus platy is one of our favorites. These little guys have everything you could want in a perfect fish: a rainbow of colors and patterns, hardiness, affordability, small size, and peacefulness with other fish and plants. Plus, they’re easy to breed for fun and can live in various temperatures and pH levels. Mix them with other fish and live plants, and you’re guaranteed to fall in love with these cuties!

Variatus platies are a joy to breed because of their endless colors and patterns. Whether you’re a seasoned fish or just starting, these fish are a great addition to your aquarium. They’re playful and lively yet gentle with other fish and plants.

So if you’re looking for a fish that’s easy to care for, fun to breed, and a delight to watch, look no further than the sunset variatus platy. They’re sure to steal your heart and become a beloved member of your aquatic family.

White Cloud Mountain Minnow


Looking for a cold water fish to add to your tank but can’t decide? We’ve got just the fish for you! Meet White Cloud Mountain Minnow, a schooling fish that’s peaceful and loves to frolic and play in swishing schools at the mid-level of the tank.

These fish are striking, with their silvery scales faintly tinged with red. The best part? They’re incredibly easy to care for and make great companions in a community tank.

White Cloud Mountain Minnow can grow up to 1.5 inches in length, require a minimum tank size of 10 gallons, and thrive in water temperatures between 64-72 °F.

So, if you’re looking for a low-maintenance and visually stunning addition to your tank, look no further than White Cloud Mountain Minnow.

Zebra Danio


The Zebra Danio is a beloved fish among freshwater aquarium enthusiasts. They’re not only stunning to look at, but they’re also incredibly low-maintenance.

These little guys are perfect for beginners. They can thrive in small, cold aquariums, and you don’t have to stress about their diet or how they’ll interact with other fish.

Watching a group of Zebra Danios swimming around is an absolute delight. Their vibrant stripes create a beautiful display as they glide through the tank.

They’ll reach about 2 inches long, making them a great option for smaller tanks. And with a minimum tank size of just 10 gallons, they’re an easy choice for anyone looking to add color to their aquatic collection. Plus, they’re perfectly content in water temperatures ranging from 64°F to 74°F.

Japanese Rice Fish


The Japanese rice fish, also known as medaka, is a cute little fish that belongs to the Oryzias genus. It’s the only genus in the Oryziinae subfamily and can be found in various places in Japan, including rice paddies, marshes, ponds, slow-moving streams, and even tide pools. This fish is incredibly versatile and can survive in freshwater and brackish water.

The scientific name for this fish is Oryzias latipes, which grows to a maximum size of 1.5 inches. It’s a relatively easy fish to care for, making it perfect for beginners. If you want to keep these fish, you’ll need a tank at least 10 gallons.

Additionally, the water temperature should remain between 64–71 °F for optimal conditions.

In summary, the Japanese rice fish, or medaka, is a fascinating and adaptable species that can thrive in various environments. Its manageable size and easy care requirements make it an excellent choice for anyone looking to get into fish keeping.

Panda Corydoras


The Panta Cory is one of the most popular fish in the aquarium scene. You can find this adorable species in many tanks all over the world.

The Corydoras panda is a type of catfish that belongs to the genus Corydoras and is a native member of the riverine fauna of South America. It’s a small fish, only reaching a size of 2 inches. Though it’s not the easiest fish to care for, it’s not too difficult either.

To keep a Panta Cory, you’ll need a minimum tank size of 10 gallons, and the water temperature should be between 68°F to 77°F. With these conditions in place, you can enjoy the beauty of this species in your aquarium.



If you’re new to the world of fishkeeping, you’ve probably heard of Guppies. They’re popular for pet fish because they’re low-maintenance and adaptable. These fish can thrive in cold and warm water environments, making them a great addition to any tank.

One of the best things about Guppies is their vast array of colors. They’re a live-bearing species, producing fry instead of eggs. However, if you have a community tank, it’s best to keep only one sex to avoid overpopulation. Guppies are also visually attractive as they swim at all tank levels.

To sum it up, Guppies (scientifically known as Poecilia reticulata) are easy to care for and come in various colors. They’re small, reaching only 1-2.5 inches as adults. These fish are adaptable to different water temperatures and can be kept in tanks as small as 10 gallons.

Bristlenose Pleco


Are you looking for a popular freshwater fish that is easy to care for? Look no further than the Bristlenose Pleco! Aquarium enthusiasts belove these little guys for their unique appearance and versatility.

Their most distinctive feature is the series of appendages that protrude from their head and nose area, giving them the nickname “Bushy Nose Pleco.”But don’t let their quirky looks fool you – these fish are tough and can thrive in almost any tank with any other species.

In fact, we recommend the Bristlenose Pleco more than any other species to our readers. They are perfect for beginners, with a manageable size of 3 to 5 inches and a minimum tank size of 25 gallons. And with a water temperature range of 60°F to 80°F, they are also great cold-water fish.

So if you’re looking for a unique and easy-to-care-for addition to your freshwater aquarium, the Bristlenose Pleco is worth considering!

Dojo Loach


These fish like to hang out at the bottom of the tank, a part of the tank that is often overlooked. Their sweet looks will catch your eye, adding new visual interest to your tank. Plus, they can even help you stay on top of weather changes! These fish are super sensitive to barometric pressure drops, so they’ll let you know when a storm is on the way.

Scientifically known as Misgurnus anguillicaudatus, these little guys can grow 6-12 inches long. They’re super low-maintenance and easy to take care of. All you need is a tank that’s at least 55 gallons and water that’s between 59-77°F.



The Axolotl has become popular in recent years thanks to its unique features. Though it’s technically a salamander, we’ve included it on our best cold-water aquarium fish list. It’s also known as the Mexican Walking Fish due to its peculiar way of moving around in the water. You’ll often see them swimming, but they also use their arms and legs to walk around the tank.

The Axolotl is quite easy to care for. They don’t require special attention and do well in tanks without a heater. They’re perfect for beginners!

They can grow anywhere from 8 to 18 inches in size. And when it comes to taking care of them, the minimum tank size you’ll need is 20 gallons. As for the water temperature, keep it between 57°F to 68°F.

Overall, the Axolotl is a unique and captivating creature perfect for those just starting in the world of fish keeping. So why not add one to your collection today?

Fancy Goldfish


These fish will stand out from the crowd with their elaborate and striking appearance. They require very little effort to keep healthy!

One of the great things about fancy goldfish is that they are perfectly suited for cold water aquariums. With natural temperature requirements as low as 50°F, they don’t even need heaters to thrive. Plus, they are known for being friendly towards other species, making them a great addition to any community tank.

While there may be some species-specific details to remember, fancy goldfish are surprisingly easy to care for overall. With a moderate difficulty level, they require minimal effort to keep happy and healthy. And with an adult size of 6-8 inches and a minimum tank size of just 20 gallons, they are perfect for any home aquarium.

So if you’re looking for a unique and low-maintenance addition to your aquarium, consider adding some fancy goldfish to your collection. With their striking appearance and easy-going nature, they are sure to be a welcome addition to any aquatic environment.

Mosquito Fish

Mosquito fish

This fish may have a less attractive name, but it is helpful! It’s known for snacking on pesky mosquito larvae, making it a popular resident in outdoor ponds. But did you know it also makes a great addition to unheated tanks?

This little fish boasts a scientific name Gambusia affinis, which is as impressive as its hardiness and can grow to be between 1.5-2.5 inches in size. The mosquito fish is also incredibly adaptable and can thrive in water temperatures ranging from 50-84°F.

While this fish is hardy and unique, it’s important to note that it can be pretty aggressive and is known to nip at fins. So, choose compatible tank mates if you consider adding them to your tank.

Asian Stone Catfish


When it comes to freshwater catfish, the Asian Stone Catfish is a crowd-pleaser. These little critters are a joy to keep in cold tanks, as they’re hardy, peaceful, and easy to care for. Plus, they’re just so darn cute!

One of the best things about these catfish is their size. They’re tiny, making them perfect for small and even nano tanks.

But don’t let their small size fool you – these catfish are packed with personality. Their unique look sets them apart from other species, with textured bodies that almost look like a computer program made them. They’re so interesting to look at, and you have difficulty spotting them in your tank!

If you’re a beginner fish keeper, the Asian Stone Catfish is an excellent choice. They’re easy to care for and only require a minimum tank size of 5-10 gallons. Plus, they’re happy in water temperatures between 64°F to 75°F. So, go ahead and add one (or a few) of these little guys to your tank – you won’t regret it!

Rosy Red Minnows


The Rosy Red Minnow may be overlooked as a feeder or bait fish, but don’t underestimate them! These exciting cold-water fish can be a great addition to your unheated tank. They’re versatile and can even thrive in outdoor ponds.

These peaceful fish tend to hang out in the middle levels of your tank and have a pretty appearance. Plus, with a scientific name like Pimephales promelas, they sound pretty fancy too!

Not only are they a visually appealing species, but they’re also easy to care for. They only grow to about 3 inches and require a minimum tank size of 15 gallons. Their preferred water temperature ranges from 50–78 °F, so they’re not too picky.

The Rosy Red Minnow is an excellent fish that deserves more attention. They’re easy to care for, visually pleasing, and can add a unique flair to your tank or pond. Give them a chance, and you won’t be disappointed!

Pygmy Sunfish


Despite its beauty and hardiness, this species remains relatively unknown to many fish enthusiasts.

Compared to other fish on the market, the Pygmy Sunfish can handle low water temperatures like a champ. With a minimum temperature requirement of just 45°F, finding another species that can match its endurance is tough.

But don’t let its hardiness fool you – the Pygmy Sunfish is an active and engaging fish that won’t sit at the bottom of your tank all day. This species is a great option for cold-water aquarists looking for something lively.

Before you decide to bring a Pygmy Sunfish into your home, it’s essential to do your research. While they’re not overly difficult to care for, there are a few key areas to remember.

With a size of just 1.25 inches, an intermediate level of difficulty, and a minimum tank size of 5-10 gallons, this species could be the perfect addition to your cold water aquarium.

Coldwater Tank Setup

Basically, cold-water fish can survive in water temperatures of 70 °F or less. They typically come from temperate and subtropical regions.

Setting up the tank for these fish is relatively easy, especially if you’ve chosen the right size for your fishy friends. However, we’ve got some tips to make it even smoother and hassle-free.


Appropriate filtration is crucial for maintaining high water quality in a cold-water aquarium. Without proper filtration, the tank water can become toxic to the fish, leading to illness and even death.

One recommended choice for filtration in cold water tanks is air-powered sponge filters. These filters do not produce heat output, which is essential for maintaining the appropriate temperature range for cold-water fish. They also provide a large surface area for beneficial bacteria to grow, which helps to break down waste and reduce ammonia levels in the water.

In addition to filtration, it is essential to regularly test the water parameters and clean the tank to ensure a healthy environment for the fish. Aquarium test kits can help determine whether the water has the right pH levels and other essential parameters for the fish.

Tank cleaning may include removing debris or waste, scrubbing the tank walls, and performing partial water changes to reduce nitrate levels. Proper temperature control is also necessary to ensure the fish thrive, as sudden temperature fluctuations can stress them and make them vulnerable to disease.

Tank Maintenance

Regular maintenance is necessary for a healthy cold water aquarium, which includes testing water parameters, cleaning the tank, and performing partial water changes to reduce nitrate levels. Testing frequency should be determined by the type of fish and the amount of waste produced.

Regular water testing helps ensure that the water is suitable for the fish and that pH levels are acceptable. Choosing the right filter is also essential to maintain a healthy environment for the fish. Air-powered sponge filters are a good choice because they don’t output heat and provide mechanical and biological filtration.

Regularly, partial water changes should be done to reduce nitrate levels and maintain water quality. This involves removing a portion of the water and replacing it with fresh, dechlorinated water.

Algae control is also essential in cold-water aquariums. While cold water tanks produce less algae than warm water tanks, it’s still necessary to maintain a healthy balance. This can be achieved through proper lighting and limiting the time the lights are on.

pH management is another essential aspect of tank maintenance. Cold-water fish can be sensitive to pH changes, so it’s important to maintain a stable pH level. Regular testing and using pH buffering products can help maintain a stable pH level.


Testing the water parameters in a cold water aquarium is crucial for maintaining a healthy environment for the fish. By using an aquarium test kit, aquarists can determine the pH levels and other parameters to ensure they are within the suitable range for the fish species.

When setting up a testing routine, aquarists should consider their aquarium’s temperature ranges and tank size, as different fish species have varying requirements.

Filtration options also play a role in water quality, and air-powered sponge filters are a good choice for cold water tanks because they do not output heat. Regular maintenance procedures such as testing the water parameters, cleaning the tank, and performing partial water changes should be followed to maintain a healthy tank.

Water cleaning may require a partial water change to reduce nitrate levels, and tank maintenance should consider the size and needs of the fish. Cold water tanks produce less algae than warm water tanks, but beneficial bacteria still develop in the filter over time and should be preserved by using old tank water to flush the filter media.

Aquarists can regularly test and maintain the water parameters to provide a healthy and thriving environment for their cold-water fish.

Water Cleaning

Taking care of your aquarium can be a fun and rewarding experience. However, it’s important to keep harmful nitrates and ammonia in check. Luckily, healthy plants in the ecosystem can help, but sometimes a partial water change is necessary.

To ensure the new water doesn’t harm your fish, ensure it’s properly conditioned and at the same temperature as the tank. A gravel vacuum can help clean the bottom of the tank and remove dirty water. Slowly add the new water to keep your fish comfortable.

If you have a cold water tank, you may have less algae than those with warm water tanks. However, even with algae feeders, occasional cleaning may still be needed. Monitor the filter media, which may need to be changed occasionally.

When cleaning the filter, always use the old tank water to avoid losing the beneficial bacteria that develop over time. These bacteria help keep your aquarium healthy and happy. With a little attention and care, your aquarium can thrive for years.

5 Key Tips for Cooling Your Coldwater Aquarium

So, you’re all caught up on how to set up a cold water tank and which fish are best suited for it. Let’s take a moment to review the 5 essential things to remember about water temperature for your unheated aquarium:

Use a thermometer

Setting up a cold water tank is like a tropical tank, except you don’t need a heater. You should lower the water temperature if you live in a place that’s always warm or have hot summers. An aquarium thermometer can help you.

Investing in an aquarium thermometer is a smart idea if you want to keep your fishies happy. It’s easy to use and can save you a lot of trouble in the long run. Plus, it’s always better to be safe than sorry.

So, whether you’re a seasoned fish owner or starting, ensure you have an aquarium thermometer.

Choose the right room or location

Keeping your fish tank cool and consistent can be as easy and budget-friendly as managing its location. Avoid placing your tank near any heat-generating appliances, such as electronics, fridges, or computers. Instead, opt for a cool room and ensure it’s not exposed to direct sunlight.

By taking care of your tank’s placement, you also take care of your aquatic inhabitants. Not only will they thrive in a cooler and consistent environment, but you’ll also avoid any potential equipment malfunctions from overheating. So, be mindful of where you position your tank and enjoy a healthy and happy aquatic community.

Choose the right lighting

Are you worried about the temperature of your aquarium water? Don’t panic. We’ve got some tips to help you out. First off, try turning off any electronics that produce heat but aren’t necessary. You don’t want to endanger your fish, so only turn off lights and other non-essential items.

If you’re still struggling to lower the temperature, it may be time to upgrade your lighting. LED lights produce less heat than traditional aquarium lights, making them a great investment for those with warm tanks.

Turn on the A/C

Did you know that the temperature of the air can directly impact the water around us? That’s right – the water we use daily, whether for drinking, washing, or swimming, is affected by the air temperature surrounding it. But don’t worry; there’s a simple solution – your trusty HVAC system or AC can help regulate the temperature and keep things comfortable.

Cool the water

An aquarium chiller is an excellent solution for cold water fish to feel the heat. But be careful! Sudden temperature changes can be fatal for fish. Always take it slow when you’re trying to lower the temperature.

Frequently Asked Questions

What is the maximum size that a Dojo Loach can reach?

The Dojo Loach can reach a maximum size of 12 inches and requires a minimum tank size of 55 gallons.

Can Bristlenose Plecos live in a tank with other fish species?

Bristlenose plecos can live with other fish species, but compatibility concerns should be considered.

What is the ideal tank size for keeping Axolotls?

The ideal tank size for axolotls is 20 gallons, with ideal filtration and tank decor allowing hiding spots.

How often should water changes be performed in a tank with Rosy Red Minnows?

Water quality is crucial for rosy red minnows, and regular water changes should be performed to maintain optimal conditions.

What are some common methods for cooling a coldwater aquarium?

Chilling techniques for coldwater aquariums include fans, ice packs, and coolers. Cooling equipment options include chillers and temperature controllers. Proper coldwater species selection and maintenance tips, such as water testing and partial water changes, can also aid in temperature control.


In conclusion, keeping cold water fish in your aquarium can be a unique and cost-effective way to enjoy an aquatic hobby. With a variety of species to choose from, ranging from beginner to expert level, there is a cold water fish for every aquarist.

It is important to consider each species’ care requirements and temperature ranges to ensure their health and happiness.

Maintaining a cold water aquarium requires attention to detail and proper tank maintenance. From setting up the tank to cooling the water temperature, there are several key tips to remember.

By following these guidelines, you can create a thriving aquatic environment and enjoy the beauty and tranquility of your cold-water fish.