11 Cold Water Fish Species Perfect for Your Freshwater Aquarium Discover top cold-water fish and tips for a thriving, unheated tank. By Shirlie Sharpe Shirlie Sharpe Shirlie Sharpe is an aquatic expert and writer with over three decades of experience keeping and raising ornamental fish. She has consulted with The Minnesota Zoo and the National Aquarium. Shirlie has also authored a book on setting up aquariums. Learn more about The Spruce Pets' Editorial Process Updated on 06/02/25 Reviewed by Nick Saint-Erne Reviewed by Nick Saint-Erne Dr. Nick Saint-Erne, DVM, is a highly accomplished veterinarian and writer who has treated zoo animals and exotic pets for more than 35 years. He has worked with the Centers for Disease Control and Prevention to improve pet store animal care among other endeavors. Dr. Saint-Erne is part of The Spruce Pets' veterinary review board. Learn more about The Spruce Pets' Veterinary Review Board Credit: The Spruce / Marina Li Key Takeaways Optimal water temperature is crucial for the health of fish in a freshwater aquarium, especially for cold-water species that can tolerate cooler conditions.Common cold-water fish like goldfish and zebra danios are popular choices, but they require different tank sizes due to their potential growth.Responsible aquarium ownership involves understanding the full-grown size of fish species to prevent problems, as well as avoiding releasing aquarium fish into the wild. One crucial factor when stocking your aquarium is the water temperature your fish require. Most ornamental aquarium fish are tropical, needing warm water between 72 and 82 degrees F (22-28 C) to survive. However, some species can thrive in cooler water, with temperatures as low as 50-60 degrees F (10-15 C). The goldfish is the most commonly kept cold-water fish, but it can grow up to a foot long, making it too large for a small aquarium. However, many other fascinating fish species thrive without a heated tank. You can find fish that prefer cold water from temperate zones across the globe. Some cold-water ornamental fish grow too large for aquariums and are better suited for outdoor ponds. Koi, for example, may be sold at a few inches long, but they can reach up to three feet as adults. If you're setting up a cold-water aquarium, consider these 11 fish species that stay at manageable sizes and thrive in cooler conditions. Tip Avoid releasing aquarium fish into the wild when they outgrow your tank. These species can disrupt local aquatic environments by outcompeting native species. Instead, donate large fish to a pet shop, public aquarium, or hobbyist with a larger tank. It's best to research a fish's potential adult size before purchasing to ensure your aquarium can accommodate them as they grow. Your Comprehensive Guide to Killifish Care and Species Diversity 01 of 11 Zebra Danio Credit: Thierry Marysael / Getty Images After the goldfish, the zebra danio (Danio rerio, Brachydanio rerio formerly) is the next most readily available of all the cold-water fish. Native to South Asia, they tolerate temperatures that fall into the mid-60s F (18 C) and are very easy to care for. Long-finned forms are available, as well as a popular leopard-spotted variety. Species Overview Length: 1 to 1.5 inchesPhysical Characteristics: Five uniform horizontal blue stripes extending to caudal fin; laterally compressed shape, with the mouth directed upward; torpedo-shaped with gold stripes between the blue (male); whitish belly with silver stripes between the blue (female) 02 of 11 White Cloud Mountain Minnow Credit: Bruno Cavignaux / Getty Images Almost extinct in its native China due to pollution, this is one of the easiest fish to care for. The white cloud minnow (Tanichthys albonubes) does best in cooler temperatures. A new gold-colored variant has become very popular, although very low temperatures will dampen their attractive coloration. Species Overview Length: 1.5 inchesPhysical Characteristics: Silver green, rosy pink, or gold body with red caudal and dorsal fin; brighter colors, slimmer in body, fan-shaped dorsal and anal fins (male); white distended abdomen, wedge-shaped fins (female). 03 of 11 Pearl Danio Credit: Marcin / Getty Images Like the zebra danio, the pearl danio (Danio albolineatus) is very hardy and easy to care for. It will tolerate temperatures into the mid-60s without difficulty and is easy to find. Pearl danios are larger than zebra danios, but they need not be kept in schools. They are native to Sumatra, Laos and Thailand. Species Overview Length: 2 inchesPhysical Characteristics: Forked tail, paired barbels, pearlescent color. 04 of 11 Bloodfin Tetra Bloodfin Tetra. Credit: Shirlie L Sharpe Natives to Southern Brazil and Paraguay, both the standard bloodfin (Aphyocharax anisitsi), and the false bloodfin (Aphyocharax dentatus) tolerate temperatures as low as the mid-60s. Peaceful omnivores, they are easy to care for and are quite hardy. As such, bloodfin tetras are offered in many pet shops. These tetras are active surface dwellers and are best kept in schools. Species Overview Length: 2 to 3 inchesPhysical Characteristics: Silvery long thin body; all fins colored red; tetras have no barbels, but have an small adipose fin on the caudal peduncle. Continue to 5 of 11 below 05 of 11 Buenos Aires Tetra Credit: Thomas R. Reich Buenos Aires tetra (Psalidodon anisitsi, formerly Hemigrammus caudovittatus) are easily found for sale and will tolerate temperatures into the mid-60s F (18 C). Choose between standard and the albino variants. Like the bloodfin tetras, they are undemanding and easy to care for. They are suitable for a community tank but will voraciously eat live plants. Species Overview Length: 2 to 3 inchesPhysical Characteristics: Silvery fish with a back of olive and brown; anal, ventral, and dorsal fins are yellowish to reddish; red upper part of the iris of the eye; a dark diamond-shaped spot near the tail fin base. 06 of 11 Gold Barb Credit: Valentin Hintikka / Getty Images The gold barb, or Chinese barb, is an extremely popular cold-water fish. Barbs are schooling fish that should be kept in groups of 5-6 fish, or more. Any aquarium containing gold barbs should maintain a moderate current. A dedicated river tank is not necessary, but some flow from a powerhead should be provided. The gold barb (Barbodes semifasciolatus, previously named Puntius semifasciolatus or Barbus schuberti), also comes in a less common green variety. Species Overview Length: 2 to 3 inchesPhysical Characteristics: Bright, shiny golden yellow body color that was developed through selective breeding. In the wild, they are greenish colored. 07 of 11 Hillstream Loach Credit: Spiketooth / Wikimedia Commons / CC BY 3.0 These striking bottom-dwelling fish (Gastromyzon punctulatus) are from South and East Asia. Although these fish are not often seen in pet shops, individuals can be found for sale from time to time. Not all of them prefer cool temperatures, but most will tolerate temperatures that fall into the mid to upper 60s F (15-20 C). Species Overview Length: Up to 3 inchesPhysical Characteristics: black and yellow, spotted along the head and back; long stripes along the sides; flattened top to bottom; wide and round pectoral and pelvic fins that form a ventral sucker. 08 of 11 Two Spot Barb Credit: Nilesh Heda / Wikimedia Commons / Public Domain This fish hails from Nepal, India, and Pakistan. The omnivorous two spot barb (Pethia ticto, formerly Barbus ticto) can be a bright red fish. The darkness of its spots and the brightness of the red lateral color match the quality of its varied diet; it is recommended to give them live food, flake food, and some algae. Counter to its name, this barb has no barbels at all. Species Overview Length: 3 to 5 inchesPhysical Characteristics: Silvery body, one black spot near the head and one near the tail; dorsal fin reddish with black spots (male); no barbels. Continue to 9 of 11 below 09 of 11 Rosy Barb Credit: Don Farrall / Getty Images Hailing from Afghanistan and Bangladesh, this little fish is tolerant of temperatures in the mid-60s Fahrenheit (18 C), or even lower. They are easy to care for and are suitable for a community aquarium. Undemanding and beautiful, the rosy barb (Pethia conchonius, formerly Barbus conchonius) is also considered one of the hardiest barbs. Species Overview Length: Up to 6 inchesPhysical Characteristics: Long thin fish with iridescent pinkish sides and large scales; ventral fins that are saturated red at the base; bluish edged anal fin with a hooked outgrowth or barb (on males). 10 of 11 Weather Loach Credit: Osaka Suido Kinenkan / Getty Images Readily available, the weather loach (Misgurnus angullicaudatus) from East Asia is one of the easiest fish to care for. Couple that with the fact that they will tolerate temperatures in the 50s F (10 C), they are excellent candidates for a cold water tank. This fish becomes more active when the barometer drops before a storm, hence the name. Species Overview Length: 5 to 8 inchesPhysical Characteristics: Pink, albino, or gray body; elongated shape like an eel; 3 sets of barbels surrounding the mouth, appearing like a mop. 11 of 11 Goldfish Originally from Asia, Goldfish (Carassius auratus) are probably the most readily available fish in captivity. There are many attractive variations of this popular and hardy fish. Fancy goldfish have long, double caudal fins (tails) that may be as long as the body. The comet goldfish has a long, single tail and is usually found in the golden coloration, but can also occur in white, orange and white, and black, orange and white coloration. Species Overview Length: 8 to 12 inchesPhysical Characteristics: Elongated bodies with a single tail fin in common, comet and shubunkin varieties. Many body shapes with twin tails, such as ryukin, and oranda goldfish. Unless you are planning on putting it into a pond, avoid the one cold-water fish known as the Chinese High-Fin Banded Shark, also called the Wimple Carp, or the Freshwater Batfish (Myxocyprinus asiaticus), referencing its high triangle-shaped dorsal fin and black banding on young fish. It is often sold at a few inches long in pet stores, but can grow to eight inches in the first year, then this cute little fish (not a shark) ultimately grows to four and a half feet long. Hence it is not appropriate for most aquaria. Explore more: Fish & Aquariums Freshwater Fish & Aquariums Freshwater Fish Breeds