Top 16 Cold Water Aquarium Fish (That Don’t Need A Heater)

Cold Water Aquarium Fish and invertebrates

Cold water aquariums aren’t just something for beginners who haven’t yet progressed to tropical tanks; they present a whole other world of fish keeping possibilities. Many species of aquarium fish simply aren’t suited to warmer waters, and for the beginner or enthusiast alike, there is a whole array of species to get you positively reeling about.

Here we take a closer look at 16 of the finest:

1. White Cloud Mountain Minnow (Tanichthys Albonubes)

White Cloud Mountain Minnow
  • Maximum Size: 4cm
  • Temperature range: 64-75°F
  • pH: 6.0-8.0
  • Level of Care: Easy
  • Tankmates: Other smaller, peaceful community fish.

These beautiful, tiny shoaling fish are a real cold water aquarium favorite. Easy to keep and highly suitable for the beginner – their dainty charm makes them a top choice for fish keepers of all levels. 

They prefer to live in shoals of six or more and will be at their brilliant best, dashing about in groups of at least ten. Due to their need for speed, this species is best kept in tanks of 20 gallons or more to allow them space to let fly. 

Even though they are fast, they can still sometimes be predated by greedy goldfish – so it is much better to keep these species apart!

In the wild, these fish inhabit shallow streams of Asia with a slow to moderate current. A dark, sandy substrate, some smooth pebbles, and stemmed plants will make them feel well cared for.

2. Fancy Goldfish (Carassius Auratus)

Fancy Goldfish
  • Maximum Size: 8 inches
  • Temperature range: 65 – 72°F
  • pH: 7.0 – 8.0 preferred
  • Level of Care: Beginner to Intermediate
  • Tankmates: Other peaceful but robust community members.

One of the most renowned of all pet fish – the fancy goldfish is a classic choice for the cold water aquarium. Varieties include Fantail, Ryukin, Lionhead, and many many more.

Whereas common goldfish get far too large and fast for most aquariums, the fancy goldfish has a much calmer and more placid character. Their smaller size makes them a good fit for tanks of 40 gallons or more for a pair, with an additional 20 gallons needed for every extra specimen.

Fancy Goldfish love interacting with each other, and should never be kept alone. Always keep them in pairs or ideally in larger groups to keep them happy. They also really appreciate regular doses of plant-based food, as the animal protein in most fish foods is only partially digestible to goldfish. 

Although this fish is a popular choice for first-time fish keepers, Fancy Goldfish will do much better under a high level of care. Proper filtration and frequent partial water changes will make all the difference for this fish – from merely surviving to truly thriving. Well looked after, your Fancy Goldfish could live for over 10 years!

3. Hillstream Loach (Beaufortia Kweichowensis)

Hillstream Loach
  • Maximum Size: Approximately 2.5 inches
  • Temperature range: 61 – 75°F
  • pH: 6.0 – 7.5 
  • Level of Care: Expert
  • Tankmates: Specialist community – other fast-flowing stream species.

The Hillstream Loach is all too often sold as a substitute for the better known Plecostomus, which, although they resemble in appearance, are quite a different fish. 

Whereas Plecostomus are in the catfish family and are very unfussy in terms of their environment, Hillstream Loaches have very particular requirements that need to be met to keep them happy and thriving. 

As they hail from very fast-moving rivers and streams of China, they demand a similar oxygen-rich and fast-flowing environment in the aquarium. This can be achieved through extra high powered filter heads, which should constantly turn the surface of the water. They also prefer to have a few other members of their own kind to keep them company.

Hillstream Loaches, however, do resemble Plecostostomus in that they are good algae eaters! They will happily clean your tank’s glass for you night and day – although it is a good idea to allow a good film of algae develop in the tank before introducing this fish to make sure they have plenty to eat.

4. Paradise Fish (Macropodus Opercularis)

  • Maximum Size: 4 inches (excluding trailing fins)
  • Temperature range: 61 – 79 °F
  • pH: 6.0 – 8.2
  • Level of Care: Intermediate
  • Tankmates: Only house with other large and robust species.
This stunning fish may be a surprising addition to our list of cold water species. Everything about its exotic, colorful appearance immediately conjures up images of the tropics. Yet, this member of the gourami family is quite happy in water temperatures right down to around 55°F.

The main consideration when it comes to hosting Paradise fish is its territorial and rather aggressive tendencies. Two males should never be kept together, and a lone male with two females is the ideal set up. Other tankmates need to be chosen very carefully, as shy, vulnerable species may easily fall victim to the male’s excessive displays of bravado!

These fish naturally occur in Oriental rice paddies, hill streams, and rivers, and one of their companions in the wild is the White Cloud Mountain Minnow. A tank with a good cover of plants and some carefully chosen pieces of driftwood will make a stunning backdrop and a good home for Paradise fish.

5. Empire Gudgeon (Hypseleotris Compressus)

Empire Gudgeon
  • Maximum Size: 4.7 Inches
  • Temperature range: 65 – 82°F
  • pH: 7-8.5
  • Level of Care: Expert
  • Tankmates: Other specialist tank members – may eat smaller fish.

Empire Gudgeon certainly make a new choice for the cold water aquarium. At their best, this fish can be absolutely stunning, but for them to feel really at home, they demand many special requirements to be met.

Empire Gudgeon hail from hard, often brackish waters of Australasia and although they do fine in freshwater, they have a strong preference for alkaline conditions, with a pH. of 7-8.5

They are also quite fussy eaters and prefer a frozen or live diet of brine shrimp, mosquito larvae, or daphnia. With time they may also accept dried food, but since this species is normally caught in the wild, it is strongly advised to offer them a menu that resembles that of their natural habitat.

To further enhance their environment, it is also important to offer them a shady, densely planted aquarium. 

It is only then, with all of their needs met, that this fish may feel at home enough to show off their astonishingly striking red fins in all of their glory. A stunning reward for the true enthusiast!

6. Galaxy Raspora (Danio Margaritatus)

Galaxy Raspora
  • Maximum Size: 1 inch
  • Temperature range: 65 – 75°F
  • pH: 7.0 – 8.0 
  • Level of Care: Easy – Intermediate 
  • Tankmates: Other smaller, peaceful species 

This tiny member of the Raspora / Danio family is a delicate little community fish, reaching only around 1 inch from tip to tail. Their beautiful grey, speckled flanks, and orange fins make them a delightful possibility for the cold water aquarium. 

Also known as the ‘Celestial Pearl Danio’ – these schooling fish need the company of their own kind and do best in groups of six or more. They may appear timid at first, but providing they are kept with well-chosen tankmates, they should feel safe enough to dash about freely in open water too.

They prefer a tank with some living plants, of at least 10 gallons. They are otherwise unfussy and will tolerate temperatures down to 65°F.

7. Weather Loach (Misgurnus Angullicaudatus)

Weather Loach
  • Maximum Size: 10 inches
  • Temperature range: 50 – 77°F
  • pH: 6 – 7.5
  • Level of Care: Intermediate
  • Tankmates: Other larger community members.

The Weather Loach is so-called because of its remarkable talent at being able to predict the weather! Frantic activity often indicates that a low-pressure front is approaching, and this uncanny sixth sense is a marvel to witness in the aquarium or its wild habitat alike. 

Also known as the ‘Dojo Loach’, the two varieties commonly available are golden or silver with black spots. Their potentially large size makes them suitable only for larger aquariums, of at least 40 gallons or more.

The Weather Loach prefers the company of its kind and will be much happier if kept in groups of six or more. They should also really be kept only on soft substrates such as sand or very fine, smooth gravel. This fish loves to dig, and their sensitive bellies were never designed to borrow into coarse, sharp gravel.

Allow them plenty of hiding places for them to sleep in the daytime, and make sure your aquarium hood is on tight, as this fish is a rather renowned escape artist!

8. Yellow Princess Rice Fish (Oryzias Latipes)

Yellow Princess Rice Fish
  • Maximum Size: 1.5 Inches
  • Temperature range: 64 – 75°F
  • pH: 6.5 – 8.5
  • Level of Care: Intermediate
  • Tankmates: Species only – or with other small, peaceful species.

This is a sub-species of the Japanese Rice Fish, which is more silver-grey than this golden selection. They are also often known as ‘Medaka Rice Fish’.

Although these Rice Fish may tolerate tropical temperatures up to 75°F, they will do much better and live longer at typical room temperature without a heater. 

Their beautiful, shimmering appearance when kept in larger shoals can be mesmerizing. This is a species that definitely should never be kept in groups of less than six, and groups of 10 or more will undoubtedly boast a much more impressive display. 

Rice Fish much prefer a dimly lit, densely planted aquarium, and ideally some driftwood to make them feel at home. Ensure a tightly fitting lid on your tank, too, as this is a fish that sometimes likes to ‘get air’! 

9. Croaking Tetra (Mimagoniates Inequalis)

  • Maximum Size: 2.5 inches 
  • Temperature range: 64 – 73°F
  • pH: 5.5 – 7.0
  • Level of Care: Easy
  • Tankmates: Other peaceful community members

This Tetra gets its intriguing name from its courtship ritual, where the male uses a modified breathing organ to make a sound resembling a frog – presumably to attract the attention of females! They will do this readily in the aquarium since they are quite easy to breed in captivity.

Although some other Tetras can tolerate temperatures down to around 70°F, this one is truly hardy and will be happy even at fairly cool room temperature. 

Strictly a schooling species, they are best accommodated in groups of at least six to ensure their well-being. As with most other tetras, these fish are very easy-going and eminently suitable for the beginner. 

10. Odessa Barb (Pethia Padamya)

Odessa Barb
  • Maximum Size: 2.75 Inches
  • Temperature range: 65 – 77°F
  • pH: 5.5 – 7.5
  • Level of Care: Easy – Intermediate
  • Tankmates: Other medium-sized, robust species.

Another beautiful schooling fish from South East Asia, the Odessa Barb, is quite happy in temperatures down to 65°F, making them a fine candidate for cold water aquariums kept at room temperature. 

The radiant red cord running right down the length of their body, coupled with their striking black vertical stripes, makes them really standout, and a shoal of well kept Odessa Barbs can be a stunning spectacle. 

They are best kept in numbers of at least six, and this will also reduce their fin nipping tendencies. If you find they are becoming boisterous with other tankmates or pecking at their fins, try to further increase the size of their shoal. This is a good measure to make them feel more secure and less likely to bother their companions. 

Given adequate space and company, this barb will live up to 3 years or more.

11. Dwarf Dragon Goby (Rhinogobius Duospilus)

  • Maximum Size: 2 inches
  • Temperature range: 64 – 77°F
  • pH: 6.0 – 8.0
  • Level of Care: Expert
  • Tankmates: Specialist community – other fast-flowing stream species

This fascinating Goby from Vietnam and China is an excellent choice for the cold water enthusiast. Not the easiest of fish to keep, the bottom-dwelling goby doesn’t much like dried foods, and so will only really flourish when fed on fresh or frozen foods such as mosquito larvae, brine shrimp and daphnia.

They also have a strong preference for fast-flowing, oxygen-rich waters, and so require an extra highly powered filtration system. Good tankmates would be others from similar environments such as Mountain Minnows and Loaches. 

Males can be territorial with one another, but any serious squabbles can be averted by giving them a spacious tank with plenty of hiding places. 

Although a 15-gallon tank is sometimes advocated for this species, they will be much happier in an aquarium with a large surface area and at least 25 gallons of water. 

12. Danios (Hardy Danio sp.)

Danios
  • Maximum Size: 2 inches
  • Temperature range: 64 – 75 °F
  • pH: 6.0 – 8.0
  • Level of Care: Easy
  • Tankmates: Almost any other reasonably peaceful species.

These include the ever-popular Zebra Danio, Leopard Danio, and Long-finned Danios.

Danios are a classic community aquarium member, of both tropical and coldwater setups. Their spritely, active nature makes them ever entertaining to watch, as they ceaselessly rush about the tank, with seemingly boundless enthusiasm! 

This fast-paced disposition means they really prefer larger aquariums, with plenty of space to move around in. Still, they will also tolerate any tank down to 20 Gallons – as an absolute minimum. 

Their natural habitat is that of streams, ditches and rice paddies, and they will enjoy any tank setup providing they are given adequate space to open up their throttle once in a while!

They are a very peaceful and hardy genus, perfect for the beginner.

13. Panda Corydoras Catfish (Corydoras Panda)

Panda Cory
  • Maximum Size: 2.5 inches
  • Temperature Range: 68-79 °F 
  • pH: 5.8 – 7.0
  • Level of Care: Intermediate
  • Tankmates: Other gentle schooling species.

Often kept in tropical aquariums, the Panda Cory is also adaptable enough to do well in an aquarium without a heater, providing the room temperature is kept reasonably warm. 

Corydoras species are renowned for their easy-going nature, endearing demeanor, and their generous habit of cleaning up any debris that falls to the aquarium floor.

Panda Corys do require a little bit more fuss, though, in that they prefer an environment that is dimly lit or at least plenty of dense foliage and caves to hide in. 

They also really appreciate additional supplements of their natural foods such as blood worms or daphnia to keep them at their adorable best. 

All Corys are great community tank members that really enjoy the company of their kind. Be sure to keep them in groups of six or more, as there’s no sadder sight in an aquarium than a lonely Cory.

14. Everglades Pygmy Sunfish (Elassoma Evergladei)

  • Maximum Size: 1.5 Inches
  • Temperature range: 61 – 72°F
  • pH: 6.0 – 7.0
  • Level of Care: Expert
  • Tankmates: Species only, or alongside other small, shy species.

The iridescent shimmer of an Everglade Pygmy Sunfish is a real sight to behold and present an outstanding possibility for the cold-water aquarium. From their exotic appearance, one might assume that this was a fish of tropical climes, yet Pygmy Sunfish actually much prefer cold water and shouldn’t be kept in a tank with a heater at all. 

Another species suitable only for the expert, the Pygmy Sunfish has unique requirements for its well being:

Firstly, it is a tiny and shy fish, that really won’t appreciate the company of boisterous companions. It is therefore usually recommended to keep them in a species tank or perhaps with one or two other gentle species too.

They also much prefer a dimly lit environment that resembles the fairly still, muddy waters that they originate from in North America. This can be achieved with a thick cover of floating plants, and in general, this is a species that will appreciate a densely planted aquarium. 

When kept in their ideal environment, Pygmy Sunfish are also fairly easy to breed. Certainly, a novel species to try out for the experienced fish keeper!

…..and a couple of favorite cold water invertebrate to cap off our list!

15. Cherry Shrimp (Neocaridina Heteropoda var. Red)

cherry shrimp
  • Maximum Size: 1.5 inches
  • Temperature range: 64 – 82°F
  • pH: 6.0 – 8.0
  • Level of Care: Easy
  • Tankmates: Other smaller invertebrates or small, peaceful fish.

Cherry shrimp are native to the mountain streams of Taiwan. In their natural habitat, water temperatures can range from anything down to 55°F, up to 86°F, so this species has a truly huge range! 

A very colorful shrimp, they make an ideal choice for first time invertebrate keepers – as they simply require a clean tank with cycled water and some living plants to keep them happy. One does, however, need to select their tank mates with careful consideration…

Since Cherry shrimps only grow to around 1.5 inches in length, they make a very tempting snack for larger species such as fancy goldfish. Therefore only accommodate them with the smallest and most peaceful fellow tankmates – such as White Cloud Mountain Minnows, Corydoras species, etc. 

Cherry Shrimps are even easy to breed, but if you’re serious about this, you’d be better off giving them their own breeding tank to protect their fry. Each individual’s lifespan is short, at only around 1-2 years.

Learn more: Your Guide to Cherry Shrimp and Their Care

16. Dwarf Crayfish (Camberellus Genus) 

  • Maximum Size: 2 inches
  • Temperature range: 65 – 80°F
  • pH: 6.5 – 8.0
  • Level of Care: Easy – Intermediate
  • Tankmates: Most small to medium-sized community fish species. 

Although most crayfish grow quite large and can pose a threat to many of your community tank members, Dwarf Crayfish are rather different. Members of the Camberellus family (including Dwarf Orange Crayfish, Mexican Dwarf Crayfish, and Cajun Dwarf Crayfish) grow no larger than around 2 inches in size and make excellent tankmates for most small to medium size community fish. 

Fairly easy to keep, they prefer a varied diet of just about any kind of food you’d feed to the other members of your tank. Try to include at least some fresh or frozen food, though, as this will help in providing all of the nutrition they need to molt successfully. 

Molting is the periodic shedding of the skin in crustaceans, and your crayfish will really appreciate some good hiding places to carry out this process in private!

Dwarf Crayfish are also easy to breed, but once again, be sure to provide as many hiding places as possible to give the fry the best possible protection from predation from other tank members. 

FAQs about Keeping Cold Water Aquarium Fish

What Exactly Is Meant by ‘Cold Water Fish and Aquariums’?

The term cold water in the context of fish keeping refers to aquariums that are kept indoors without an aquarium heater. 

The definition of this, of course, depends a lot on the ambient temperature of the room where the aquarium is to be located. All of the fish in our list are suited to room-temperatures down to 70°F, and some of them much cooler than that. 

What Are the Differences Between Keeping Tropical Freshwater Fish and Cold Water Fish?

Most of the considerations are the same for keeping a freshwater tank, with or without a heater – just so long as you make sure your room temperature is kept within the appropriate range.

Some of the plants sold for tropical tanks may not be suitable for cold water environments; however, and cold-water conditions can also potentially host different pests and diseases to warmer water. 

What Are the Advantages of Keeping a Cold Water Tank, Over a Tropical One?

Although there are many tropical fish unsuitable for cold water conditions, there are also a myriad of species that can only be kept at lower temperatures.

Cold water fish keeping allows you to host some very remarkable species that wouldn’t be feasible in a heated tank. Keeping fish without a heater also saves on energy and your electricity bill!

…Now That We’ve Broken the Ice!

Having read through our list of cold water aquarium species, we are sure there will be something for everybody to get excited about. Cold water tanks offer much more than just a saving on your energy bill – they present an enjoyable challenge for the hobbyist to create something truly unique and special.

Stocked with care and consideration, the cold water aquarium may even exceed the marvel of its tropical counterpart.

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