Cold water fish are aquatic species that thrive in lower temperature environments, typically between 50°F and 75°F (10°C to 24°C). Unlike tropical species that require heated tanks, these hardy swimmers prefer cooler conditions that more closely resemble temperate ponds, lakes, and streams.
Why choose Cold Water Fish for your aquarium? They offer numerous advantages for both beginner and experienced aquarists. First, cold water fish tanks generally require less equipment—no heaters mean lower electricity costs and fewer components that could potentially fail. Many cold water species are also incredibly resilient, making them perfect for beginners learning the ropes of fishkeeping. Additionally, cold water aquariums can recreate beautiful natural environments with unique plant life and distinctive fish behaviors not seen in tropical setups.
Whether you’re setting up your first tank or expanding your aquatic hobby, this comprehensive guide will provide everything you need to know about selecting, caring for, and maintaining healthy cold water fish and their habitats.
Comprehensive List of Cold Water Fish Species
1. Goldfish (Carassius auratus)
Common Name(s): Common Goldfish, Fancy Goldfish (numerous varieties)
Size: 6-14 inches (depending on variety)
Lifespan: 10-15 years (up to 30+ years with excellent care)
Temperament: Peaceful, social
Ideal Tank Conditions: 65-72°F (18-22°C), pH 7.0-7.4, medium hardness
Diet: Omnivorous – quality goldfish pellets, flakes, frozen foods, vegetables
Compatibility: Best with other goldfish varieties or peaceful cold water species
Breeding Information: Egg scatterers; breed in spring when temperatures increase
Special Care Requirements: Need excellent filtration due to high waste production; require minimum of 20 gallons for single common goldfish, more for multiple or fancy varieties
2. White Cloud Mountain Minnow (Tanichthys albonubes)
Common Name(s): WCMM, Chinese Danio
Size: 1.5-2 inches
Lifespan: 5-7 years
Temperament: Peaceful, active schooling fish
Ideal Tank Conditions: 60-72°F (15-22°C), pH 6.5-7.5, soft to medium hardness
Diet: Omnivorous – quality flakes, small pellets, frozen and live foods
Compatibility: Excellent with other peaceful cold water species; keep in groups of 6+
Breeding Information: Easy breeders; egg scatterers that benefit from plants for fry protection
Special Care Requirements: Prefer well-planted tanks with moderate flow
3. Weather Loach (Misgurnus anguillicaudatus)
Common Name(s): Dojo Loach, Pond Loach
Size: 6-12 inches
Lifespan: 10-15 years
Temperament: Peaceful, active, social
Ideal Tank Conditions: 50-75°F (10-24°C), pH 6.5-7.5, soft to medium hardness
Diet: Omnivorous – bottom feeder tablets, frozen foods, vegetables
Compatibility: Gets along with most peaceful fish; best kept with other non-aggressive species
Breeding Information: Difficult in home aquariums; requires specific conditions
Special Care Requirements: Need smooth substrate to protect sensitive barbels; require secure tank lids as they can escape
4. Rosy Red Minnow (Pimephales promelas)
Common Name(s): Fathead Minnow
Size: 2-3 inches
Lifespan: 2-3 years
Temperament: Peaceful, schooling fish
Ideal Tank Conditions: 50-70°F (10-21°C), pH 7.0-7.8, medium hardness
Diet: Omnivorous – quality flakes, small pellets, frozen foods
Compatibility: Good with other peaceful cold water species
Breeding Information: Males develop breeding tubercles; and deposit eggs on the undersides of objects
Special Care Requirements: Keep in groups of 6+ for best behavior
5. Rice Fish (Oryzias latipes)
Common Name(s): Japanese Medaka, Japanese Killifish
Size: 1-1.5 inches
Lifespan: 3-5 years
Temperament: Peaceful, active
Ideal Tank Conditions: 60-75°F (15-24°C), pH 6.8-8.0, medium hardness
Diet: Omnivorous – small flakes, micro pellets, daphnia, brine shrimp
Compatibility: Peaceful community fish; works well with other small, gentle species
Breeding Information: Easy breeders; females carry eggs externally before attaching them to plants
Special Care Requirements: Benefit from floating plants; prefer still to slow-moving water
6. Paradise Fish (Macropodus opercularis)
Common Name(s): Paradise Gourami
Size: 2-3 inches
Lifespan: 6-8 years
Temperament: Semi-aggressive, territorial
Ideal Tank Conditions: 60-75°F (15-24°C), pH 6.0-8.0, soft to medium hardness
Diet: Carnivorous – quality pellets, frozen and live foods
Compatibility: Best as a single specimen or with larger peaceful fish; males fight with each other
Breeding Information: Bubble nest builders; males care for eggs and fry
Special Care Requirements: Need access to surface air; prefer planted tanks with hiding spots
7. Hillstream Loach (Sewellia lineolata)
Common Name(s): Reticulated Hillstream Loach, Tiger Loach
Size: 2-3 inches
Lifespan: 8-10 years
Temperament: Peaceful, shy
Ideal Tank Conditions: 65-75°F (18-24°C), pH 6.5-7.5, high oxygen levels, strong current
Diet: Omnivorous – algae, biofilm, quality sinking pellets, vegetables
Compatibility: Good with other peaceful species that enjoy current
Breeding Information: Very difficult in home aquariums
Special Care Requirements: Need highly oxygenated water with strong current; prefer smooth rocks and driftwood for grazing
8. Variatus Platy (Xiphophorus variatus)
Common Name(s): Variable Platy
Size: 2-3 inches
Lifespan: 3-5 years
Temperament: Peaceful, active
Ideal Tank Conditions: 65-75°F (18-24°C), pH 7.0-8.2, medium to hard water
Diet: Omnivorous – quality flakes, small pellets, vegetables, frozen foods
Compatibility: Excellent community fish
Breeding Information: Livebearers; easily breed in community tanks
Special Care Requirements: Benefit from plants and hiding spots; females need refuge from persistent males
9. Cherry Shrimp (Neocaridina davidi)
Common Name(s): Red Cherry Shrimp, RCS
Size: 1-1.5 inches
Lifespan: 1-2 years
Temperament: Peaceful, scavengers
Ideal Tank Conditions: 60-75°F (15-24°C), pH 6.5-8.0, medium hardness
Diet: Omnivorous – algae, biofilm, quality shrimp pellets, blanched vegetables
Compatibility: Works well with small, peaceful fish; avoid predatory species
Breeding Information: Easy breeders; females carry eggs under the tail until hatching
Special Care Requirements: Need mature tank with established biofilm; sensitive to copper and sudden parameter changes
10. Dace (Leuciscus leuciscus)
Common Name(s): Common Dace
Size: 8-12 inches
Lifespan: 8-10 years
Temperament: Active, schooling fish
Ideal Tank Conditions: 50-65°F (10-18°C), pH 6.5-7.5, medium hardness
Diet: Omnivorous – quality pellets, frozen foods, insects
Compatibility: Best with other larger, peaceful cold water species
Breeding Information: Difficult in home aquariums; typically breed in stream conditions
Special Care Requirements: Need spacious tanks with good filtration and water movement
11. Rosy Barb (Pethia conchonius)
Common Name(s): Red Barb
Size: 4-6 inches
Lifespan: 5-7 years
Temperament: Semi-aggressive, active schooling fish
Ideal Tank Conditions: 64-75°F (18-24°C), pH 6.0-7.0, soft to medium hardness
Diet: Omnivorous – quality flakes, pellets, frozen and live foods
Compatibility: Good with similar-sized peaceful to semi-aggressive fish; keep in groups of 6+
Breeding Information: Egg scatterers; separate breeding tank recommended
Special Care Requirements: Need swimming space and hiding spots
12. Bloodfin Tetra (Aphyocharax anisitsi)
Common Name(s): Argentine Bloodfin
Size: 1.5-2 inches
Lifespan: 5-7 years
Temperament: Peaceful, active schooling fish
Ideal Tank Conditions: 64-75°F (18-24°C), pH 6.0-7.5, soft to medium hardness
Diet: Omnivorous – quality flakes, small pellets, frozen foods
Compatibility: Excellent community fish; keep in groups of 8+
Breeding Information: Egg scatterers; separate breeding tank with fine-leaved plants recommended
Special Care Requirements: Need open swimming space with planted areas for security
13. Zebra Danio (Danio rerio)
Common Name(s): Zebrafish
Size: 2-2.5 inches
Lifespan: 3-5 years
Temperament: Peaceful, active schooling fish
Ideal Tank Conditions: 64-75°F (18-24°C), pH 6.5-7.5, soft to medium hardness
Diet: Omnivorous – quality flakes, small pellets, frozen and live foods
Compatibility: Great community fish; keep in groups of 6+
Breeding Information: Easy breeders; egg scatterers
Special Care Requirements: Need swimming space with moderate flow; prefer planted tanks
14. American Flagfish (Jordanella floridae)
Common Name(s): Florida Flagfish
Size: 2-2.5 inches
Lifespan: 3-4 years
Temperament: Semi-aggressive, territorial
Ideal Tank Conditions: 64-75°F (18-24°C), pH 7.0-8.2, medium hardness
Diet: Omnivorous – quality flakes, pellets, frozen foods, algae
Compatibility: Best with similar-sized peaceful to semi-aggressive fish
Breeding Information: Egg depositors; males guard eggs and fry
Special Care Requirements: Need territorial boundaries with plants and decorations
15. Odessa Barb (Pethia padamya)
Common Name(s): Scarlet Barb
Size: 2-3 inches
Lifespan: 4-5 years
Temperament: Semi-aggressive, active schooling fish
Ideal Tank Conditions: 64-75°F (18-24°C), pH 6.5-7.5, soft to medium hardness
Diet: Omnivorous – quality flakes, pellets, frozen and live foods
Compatibility: Good with similar-sized peaceful to semi-aggressive fish; keep in groups of 6+
Breeding Information: Egg scatterers; separate breeding tank recommended
Special Care Requirements: Need swimming space with hiding spots
16. Pond Snail (Lymnaea stagnalis)
Common Name(s): Great Pond Snail
Size: 1-2 inches
Lifespan: 1-3 years
Temperament: Peaceful, algae eater
Ideal Tank Conditions: 50-75°F (10-24°C), pH 7.0-8.0, medium to hard water
Diet: Herbivorous – algae, plant matter, bottom feeder tablets
Compatibility: Works well with most fish; may become prey for some species
Breeding Information: Hermaphrodites; lay egg clusters above the water line
Special Care Requirements: Need calcium in water for healthy shell growth
17. Rainbow Shiner (Notropis chrosomus)
Common Name(s): Rainbow Dace
Size: 2-3 inches
Lifespan: 3-4 years
Temperament: Peaceful, active schooling fish
Ideal Tank Conditions: 50-70°F (10-21°C), pH 6.5-7.5, medium hardness
Diet: Omnivorous – quality flakes, small pellets, frozen and live foods
Compatibility: Good with other peaceful cold water species; keep in groups of 8+
Breeding Information: Difficult in home aquariums; require specific stream-like conditions
Special Care Requirements: Need excellent water quality with moderate to strong currents
18. Gold Barb (Puntius semifasciolatus)
Common Name(s): Chinese Barb
Size: 2-3 inches
Lifespan: 5-7 years
Temperament: Peaceful, active schooling fish
Ideal Tank Conditions: 64-75°F (18-24°C), pH 6.0-7.5, soft to medium hardness
Diet: Omnivorous – quality flakes, pellets, frozen and live foods
Compatibility: Excellent community fish; keep in groups of 6+
Breeding Information: Egg scatterers; separate breeding tank recommended
Special Care Requirements: Need swimming space with planted areas for security
19. Celestial Pearl Danio (Danio margaritatus)
Common Name(s): Galaxy Rasbora, CPD
Size: 1 inch
Lifespan: 3-5 years
Temperament: Peaceful, shy
Ideal Tank Conditions: 65-75°F (18-24°C), pH 6.5-7.5, soft to medium hardness
Diet: Omnivorous – quality micro pellets, crushed flakes, small frozen foods
Compatibility: Good with other small, peaceful species; keep in groups of 8+
Breeding Information: Egg scatterers; benefit from dense vegetation for natural breeding
Special Care Requirements: Need well-planted tanks with hiding spots; prefer subdued lighting
20. Axolotl (Ambystoma mexicanum)
Common Name(s): Mexican Walking Fish
Size: 9-12 inches
Lifespan: 10-15 years
Temperament: Peaceful, sedentary
Ideal Tank Conditions: 60-64°F (15-18°C), pH 6.5-7.5, medium hardness
Diet: Carnivorous – earthworms, bloodworms, axolotl pellets, small pieces of fish/shrimp
Compatibility: Best kept in species-only tanks; may eat smaller tank mates
Breeding Information: External fertilization; females lay eggs on plants and surfaces
Special Care Requirements: Need fine sand substrate to prevent ingestion injuries; sensitive to temperatures above 70°F; require excellent filtration with minimal current
Cold Water Fish Care Guide
Tank Size and Setup
Setting up the proper tank for your cold water fish is crucial for their health and happiness. Unlike common misconceptions, most cold-water fish require larger tanks than their tropical counterparts due to their activity levels and waste production.
| Fish Type | Minimum Tank Size | Recommended Size |
|---|---|---|
| Goldfish | 30+ gallons depending on the species | 10+ additional gallons per fish |
| Small Schooling Fish | 10 gallons | 20+ gallons for proper schools |
| Loaches | 20 gallons | 30+ gallons depending on species |
For the best cold water fish tank setup, consider:
- Longer tanks rather than taller ones provide more swimming space and surface area for oxygen exchange
- Strong filtration system rated for at least twice your tank’s volume
- The secure lid as many cold water species are jumpers
Filtration
Cold water fish, particularly goldfish, are known for producing large amounts of waste. Proper filtration is essential for maintaining water quality and preventing toxic ammonia and nitrite buildup.
Recommended filtration options:
- Canister filters: Best for larger tanks, providing mechanical, chemical, and biological filtration
- Hang-on-back filters: Good for medium-sized tanks, easy to maintain
- Sponge filters: Excellent biological filtration, gentle flow for smaller species
For optimal results, your filter should cycle the tank’s entire water volume at least 4-6 times per hour.
Lighting
While cold water fish don’t have specific lighting requirements, proper lighting is essential for plant growth and establishing a natural day-night cycle.
Lighting considerations:
- LED lights are energy-efficient and produce less heat
- 8-10 hours of light daily is sufficient for most setups
- Timer-controlled lighting prevents algae overgrowth and maintains routine
- For planted tanks, choose lights with appropriate PAR values for your plant species
Substrate
Your substrate choice affects both aesthetics and water chemistry. Options include:
- Fine gravel: Good all-purpose choice, easy to clean
- Sand: Excellent for burrowing species like weather loaches
- Larger pebbles: Decorative but can trap debris
- Specialized planted substrates: Best for heavily planted tanks
For goldfish tanks, choose smooth substrates to prevent injury as they forage along the bottom.
Plants and Decorations
Cold water tanks can host a variety of plants that thrive in lower temperatures:
- Anubias varieties: Extremely hardy, tolerate cooler temperatures
- Java Fern: Nearly indestructible, attaches to hardscape
- Hornwort: Fast-growing floating plant that helps control algae
- Elodea/Anacharis: Oxygenating plant that thrives in cooler water
- Cryptocoryne wendtii: Adaptable to various conditions including cooler water
For decorations, include:
- Driftwood: Provides hiding spots and a natural look
- Smooth rocks and caves: Creates territories and shelter
- Floating logs: Popular resting spots for many species
Water Changes
Regular water changes, particularly waste-heavy species like goldfish, are essential for cold water fish.
Water change schedule:
- Weekly 25-30% water changes for most tanks
- Up to 50% weekly for heavily stocked goldfish tanks
- Always treat tap water with conditioner to remove chlorine/chloramine
- Match the temperature of new water to the tank temperature to prevent shock
Important parameters to monitor:
- Ammonia: 0 ppm
- Nitrite: 0 ppm
- Nitrate: <40 ppm (ideally <20 ppm)
- pH: Species dependent, typically 6.5-8.0
- Temperature: Species dependent, typically 60-75°F (15-24°C)
Feeding
Cold water fish typically have slower metabolisms than tropical species, especially at lower temperatures. Feeding guidelines:
- Feed smaller amounts 1-2 times daily
- Only provide what can be consumed in 2-3 minutes
- Reduce feeding frequency when temperatures drop below 60°F (15°C)
- Include variety: quality commercial foods, frozen foods, and vegetables
- Specific foods for cold water species contain less protein and more easily digestible ingredients
Common Cold Water Fish Diseases and Treatments
Ich (White Spot Disease)
Symptoms: White spots resembling salt grains on body, fins, and gills; flashing against objects; lethargy
Prevention:
- Maintain excellent water quality
- Quarantine new fish for 2-4 weeks
- Avoid sudden temperature fluctuations
Treatment:
- Gradually raise temperature to 75°F (if species can tolerate it)
- Medications containing malachite green or formalin
- Salt treatment (1-3 tsp per gallon) for salt-tolerant species
Fin Rot
Symptoms: Frayed, discolored fin edges; fins appear to be “melting away”
Prevention:
- Maintain clean water conditions
- Avoid fin-nipping tankmates
- Provide proper nutrition
Treatment:
- Improve water quality with more frequent water changes
- Antibacterial medications containing erythromycin or tetracycline
- In severe cases, veterinary-prescribed antibiotics
Flukes
Symptoms: Excessive mucus production; flashing; rapid gill movement; lethargy
Prevention:
- Quarantine new fish and plants
- Maintain stable water parameters
Treatment:
- Medications containing praziquantel
- Follow the full treatment course even if symptoms improve
Dropsy
Symptoms: Pinecone-like scale protrusion; bloated appearance; lethargy
Prevention:
- Maintain excellent water quality
- Provide proper nutrition
- Avoid overcrowding
Treatment:
- Isolate affected fish
- Epsom salt baths (1 tbsp per 5 gallons)
- Broad-spectrum antibiotics (often difficult to treat successfully)
Troubleshooting Common Problems
Cloudy Water
Causes:
- Bacterial bloom during cycling
- Overfeeding
- Poor filtration
- Stirred substrate
Solutions:
- Complete the nitrogen cycle before adding fish
- Feed appropriate amounts
- Upgrade filtration if necessary
- Perform partial water changes
- Add polishing filter media
Algae Growth
Causes:
- Excessive light
- Nutrient imbalance
- Poor maintenance
Solutions:
- Reduce the lighting period to 6-8 hours
- Control nutrient levels with regular water changes
- Add fast-growing plants to compete with algae
- Consider algae-eating species compatible with cold water
- Manual removal during water changes
Fish Not Eating
Causes:
- Poor water quality
- Stress
- Illness
- Inappropriate food
Solutions:
- Test water parameters and correct issues
- Ensure compatible tankmates
- Provide a variety of high-quality foods
- Try live or frozen foods to stimulate appetite
- Check for signs of disease
FAQs
Q: Can tropical fish and cold water fish live together?
A: Generally not recommended. Tropical fish require higher temperatures (75-82°F/24-28°C) than most cold water species prefer. Keeping them together would stress one group or the other, leading to health problems and shortened lifespans.
Q: Do I need a heater for cold water fish?
A: Most cold water fish don’t require heaters if your home maintains stable temperatures. However, a small heater set to a low temperature might help prevent extreme fluctuations in rooms with variable temperatures, particularly during winter.
Q: How many goldfish can I keep in a 20-gallon tank?
A: A 20-gallon tank is suitable for only one common or comet goldfish, or potentially two smaller fancy goldfish varieties. Goldfish produce significant waste and grow quite large, requiring more space than most aquarists realize.
Q: Which cold water fish are best for beginners?
A: White Cloud Mountain Minnows, Zebra Danios, and certain varieties of fancy goldfish are excellent choices for beginners due to their hardiness, adaptability, and relatively straightforward care requirements.
Q: Can cold water fish survive in an outdoor pond year-round?
A: Some species like goldfish, koi, and certain minnows can survive outdoors year-round in appropriate climates if the pond is deep enough (at least 18-24 inches) to prevent complete freezing. However, this depends heavily on your local climate and specific species requirements.
Conclusion
Cold water fish offer a fascinating and rewarding alternative to tropical aquariums. With their unique adaptations, striking appearances, and often hardier constitutions, they provide excellent options for both novice and experienced aquarists. From classic goldfish to lesser-known gems like the Rainbow Shiner or Hillstream Loach, cold water species bring tremendous diversity to the hobby.
Remember that successful cold water fishkeeping relies on understanding each species’ specific needs, providing adequate space, maintaining excellent water quality, and creating an environment that mimics their natural habitat. By following the guidelines in this ultimate cold water fish care guide, you’ll be well-equipped to create a thriving aquatic ecosystem that will bring enjoyment for years to come.
Whether you’re drawn to the elegant swimming patterns of goldfish, the playful antics of weather loaches, or the shimmering schools of white clouds, the world of cold water aquariums offers endless possibilities for aquatic exploration and enjoyment. Your cold water aquarium journey starts here—dive in!
