We are reader supported. When you purchase through links on our site, we may earn an affiliate commission. Also, as an Amazon affiliate, we earn from qualifying purchases.
You absolutely can aquascape a coldwater aquarium. In fact, cool water can make plants grow more slowly and steadily, which means less trimming and fewer big changes to your layout. The key is picking the right fish, the right plants, and building your scape to fit the conditions of a tank that runs without a heater or at room temperature. This guide will walk you through what works, what to avoid, and how to put together a beautiful, low-stress coldwater aquascape that thrives for months and years.
Can You Aquascape a Coldwater Aquarium?
Yes. Aquascaping is not only for heated, tropical tanks. Many plants and fish are happy in cooler, unheated water. In the hobby, “coldwater” often means temperate tanks that run between about 15–22°C (59–72°F), sometimes a bit higher in summer. Truly cold tanks under 15°C (59°F) are more specialized and limit both plant and livestock choices.
As long as you plan around the temperature range and choose compatible species, you can achieve natural scapes with lush greenery, graceful wood, and textured rocks—just like in a tropical setup.
Plan First: Fish-First, Then Plants
Choose Your Temperature Band
Pick the temperature your room and tank will realistically sit at most of the year. For most homes, an unheated aquarium will hover around 18–22°C (64–72°F). That is perfect for many temperate fish and a big list of plants. If your room gets colder than that in winter, you may need to select tougher species or add a small, low setpoint heater for stability.
Good Coldwater-Friendly Fish Choices
Pick fish that stay healthy and behave well in planted tanks. These are proven options for cooler water:
– White Cloud Mountain Minnows (Tanichthys albonubes): Peaceful, plant-safe, like 16–22°C. Great for schools in a gentle-flow tank.
– Medaka Ricefish (Oryzias latipes): Hardy, active, enjoy 15–28°C, plant-safe, and come in nice colors.
– Paradise Fish (Macropodus opercularis): 18–24°C, striking fish. Keep one male with care; they can be territorial.
– Variatus Platy (Xiphophorus variatus): 18–25°C, hardy livebearers that leave most plants alone.
– Hillstream Loaches (Sewellia, Gastromyzon): 18–24°C, need strong flow and high oxygen. They graze biofilm and look great on boulders.
– Native temperate species (where legal): Such as dace or shiners in cooler water, but research local regulations and needs.
Goldfish deserve a special note: Fancies do well at 18–22°C and can be aquascaped around, but they are big, messy, and often eat or uproot plants. If you want a lush carpet or delicate stems, choose other fish. If you love goldfish, you can still achieve a beautiful “hardscape-forward” look with tough plants—more on that below.
Plants That Thrive in Cooler Water
Easy Epiphytes to Attach to Wood and Rock
These plants do not need to be buried and will tolerate cooler temps. They are ideal for goldfish tanks and for scapes that rely on hardscape:
– Anubias (nana, barteri, coffeefolia): Thick leaves, slow growth, happy in 18–24°C. Attach rhizomes to rocks or driftwood.
– Java Fern (Microsorum pteropus): Very hardy, tolerates low light and cool water. Many varieties like ‘Windelov’ or ‘Trident.’
– Bolbitis heudelotii (African water fern): Likes soft, cooler water and good flow. Attach to wood and provide moderate light.
– Java Moss (Taxiphyllum barbieri) and Christmas Moss: Great for texture and shrimp grazing; do well in cooler water.
– Willow Moss (Fontinalis antipyretica): A true coolwater moss, lovely in stream-style aquascapes.
Stems and Rosettes That Handle Temperate Temperatures
Many common aquarium plants will grow fine around 18–22°C, though they may be slower:
– Vallisneria (italiana, spiralis): Classic ribbon plant, tolerates hard, alkaline water. Good for background grass effect.
– Sagittaria subulata: Compact grass-like rosette for foreground and midground meadows.
– Elodea/Anacharis (Egeria densa): Pond staple that thrives in cooler water; great for fast nutrient uptake.
– Hornwort (Ceratophyllum demersum): Floats or anchors lightly, very fast-growing, excellent for new tanks.
– Water Sprite (Ceratopteris thalictroides): Can be rooted or floating; shade provider; grows in temperate setups.
– Bacopa (monnieri or caroliniana): Straightforward stem; tolerates a wide temperature range.
– Cryptocoryne species: Many do well around 20–24°C; at the lower end growth slows and some may “melt” then recover. Choose easier species like C. wendtii and give them time.
Floating Plants and Cold-Tolerant Oddballs
– Frogbit (Limnobium laevigatum): Helps with algae by shading; likes calm surface and moderate temps.
– Duckweed (Lemna): Very tolerant and great for nutrient control, but it spreads fast—use with intention.
– Riccia fluitans: A bright green cushion if trapped on rocks or floats freely.
– Marimo “Moss” Balls (Aegagropila linnaei): Actually algae; prefer cooler water and gentle flow.
Plants to Avoid or Use Carefully in Cold Tanks
– Delicate carpets like dwarf baby tears (Hemianthus callitrichoides) often struggle without CO2 and warmth.
– Hot-water lovers like many Rotala and Ludwigia species may stall or melt under 18–20°C.
– Bulb plants that prefer warmth (some Aponogeton species) may go dormant in cool water.
If in doubt, start with the tough list above, then experiment slowly.
Hardscape and Substrate Choices
Substrate Strategy: Match It to Your Fish
– For goldfish: Use soft sand or very large, smooth gravel that cannot be swallowed. Plant in pots or under heavy stones, and consider root tabs inside pots rather than loose soil; goldfish love to dig.
– For small community temperate fish: A planted substrate (aquasoil) capped with fine sand or just aquasoil alone works well. If you prefer inert sand or gravel, add root tabs under heavy root feeders like crypts and vals.
Cooler water slows plant metabolism, so you do not need ultra-rich soil. A moderate, stable substrate with occasional fertilization is plenty for low-tech tanks.
Rock and Wood Tips
– Rock types: Seiryu stone can raise KH and pH slightly due to calcium content—great if you keep hard-water fish or goldfish, less ideal if you need soft water. Dragon stone is inert and easy to stack. Test unknown rocks with vinegar (fizzing indicates carbonates).
– Driftwood: Spider wood or manzanita add natural flow and attachment points. Soak first to reduce buoyancy and tannins.
– Safety: Avoid sharp edges for goldfish and active swimmers. Sand any rough points or choose rounded stones.
Anchoring Plants So They Stay Put
Use plant weights, small piles of pebbles, or cyanoacrylate gel (super glue gel) to attach epiphytes and moss to wood and rock. For rooted plants in goldfish tanks, place them in ceramic or plastic pots with pebbles on top, then hide the pots with hardscape.
Equipment and Water Parameters
Lighting and Photoperiod
Coldwater aquascapes are usually low to medium light. Aim for 6–8 hours daily to start. Use a full-spectrum LED around 6,000–7,000K. If you see algae, reduce to 6 hours, add floaters, or dim the light. Plants grow more slowly in cool water, so you do not need intense lighting unless you choose demanding species.
Filtration and Flow
Good filtration is essential because beneficial bacteria slow down in colder water, especially below 16°C. Use a filter rated for at least 5–8 times your tank volume per hour. For goldfish, go higher and clean prefilters often. For hillstream loaches, create a strong current with powerheads and consider a river manifold setup for high oxygen and turnover.
Heating and Cooling Management
– Most “coldwater” aquaria are unheated but stable. If your room dips under 15°C often, add a small heater set to 18°C for stability.
– In summer, prevent overheating. Aim to keep below 24–25°C for temperate species. Use clip-on fans for evaporative cooling, increase surface agitation, and turn on air stones. If needed, float ice packs in a bag for short periods; do not cause big temperature swings.
CO2 and Fertilization in Cool Water
CO2 is optional. Cooler water holds more dissolved CO2 naturally, and many cold-tolerant plants are happy in low-tech setups. If you add CO2, growth will be faster, but watch fish carefully and ensure strong surface agitation for oxygen. Fertilize lightly:
– Micronutrients once or twice weekly at half tropical doses.
– Root tabs every 2–3 months under heavy feeders.
– Let fish waste supply much of the nitrogen and phosphorus; supplement only if you see deficiencies.
Step-by-Step Aquascaping Guide
1) Design the Layout
Sketch a plan. Decide on a style: a grassy valley for minnows, a boulder stream for hillstreams, or a hardscape-centric goldfish riverbed. Choose a focal point (Golden Ratio or Rule of Thirds). Keep open swimming lanes, especially for active fish or goldfish.
2) Dry Start or Wet Start?
Dry start methods are popular for carpet plants, but many cold-tolerant carpets are limited. Most coldwater scapes do best with a wet start:
– Place substrate and hardscape securely.
– Mist epiphytes and mosses as you position them.
– Slowly fill the tank over plastic wrap to avoid disturbing the layout.
3) Planting Day
Trim plant roots to 2–3 cm. For stems, plant in small groups with space in between so light can reach lower leaves. Attach epiphytes with glue gel in tiny dots on stone and wood. Weight down floaters at first if needed, then release after a week.
If you keep goldfish, pre-pot rooted plants and bury the pots behind rocks. Add larger stones around the base to deter digging.
4) Cycle and Stocking Timeline
– Week 0–1: Start the filter, add bottled bacteria if you wish, and run lights at 6 hours. Add a small pinch of food daily or pure ammonia to feed the bacteria.
– Week 2–4: Test ammonia and nitrite until both read zero within 24 hours of dosing. Add your first hardy fish group. Keep feeding light and steady.
– Week 5–8: Add the remainder of your fish slowly. Increase light to 7–8 hours only if algae is under control and plants are growing.
Water Parameters to Aim For
General Ranges
– Temperature: 18–22°C for most temperate community fish; 20–23°C for fancy goldfish; 18–22°C with strong flow for hillstream loaches.
– pH: 6.8–7.8 for most cold-tolerant plants and community fish; 7.2–8.0 for goldfish.
– GH/KH: Moderate hardness (GH 6–12, KH 4–10) is fine for most. Goldfish prefer harder, alkaline water. Choose plants tolerant of harder water like anubias, java fern, vals, and hornwort.
Maintenance Routine
Pruning and Replanting
In cooler water, plants grow slower, which is great for low-maintenance tanks. Trim stems when they reach the surface and replant the healthy tops. Thin out floaters weekly so they do not block all light. Remove dying leaves promptly to prevent algae growth.
Water Changes and Filter Care
Perform 30–50 percent water changes weekly, especially with goldfish. Vacuum lightly around plants; do not uproot them. Rinse filter media gently in old tank water monthly to avoid killing beneficial bacteria, and clean prefilters more often if you have messy fish.
Algae Control in Cool Tanks
Diatoms (brown algae) are common early on, especially in cooler water. They usually fade after the tank matures. Keep the light modest, limit nutrients, and add nerite snails if compatible. If green hair algae appears, shorten the photoperiod, improve flow, and remove by hand. Avoid algae-eating fish that prefer warm water; stick to snails and shrimp in non-goldfish community tanks.
Three Example Coldwater Aquascapes
1) Goldfish River Zen
– Tank: 200 liters or larger for two fancy goldfish. Goldfish are big; give them room.
– Hardscape: Rounded river stones and driftwood arranged to make wide swimming lanes. Avoid sharp edges.
– Plants: Anubias and java fern attached to rocks and wood, bolbitis in shaded areas, hornwort as a floating nutrient sponge. Marimo balls scattered for texture.
– Substrate: Soft sand; potted vallisneria behind stones if you want background greens. Use stone rings to protect roots.
– Care: Heavy filtration, frequent water changes, and occasional re-anchoring as goldfish explore. Expect a serene, natural look that holds up to goldfish behavior.
2) Mountain Minnow Meadow
– Tank: 60–90 liters with a school of 12–20 White Cloud Mountain Minnows.
– Hardscape: Light-colored dragon stone framing a central valley. A few branches of spider wood for height.
– Plants: Sagittaria subulata and vallisneria for grasses, bacopa in the rear corners, java moss on wood tips, and frogbit for soft shade.
– Substrate: Nutrient-rich soil capped with sand or just aquasoil. Add root tabs under the sag and vals every 2–3 months.
– Care: Moderate light for 7 hours, gentle flow, weekly trims to keep the “meadow” tidy. Expect active, colorful schooling behavior above a soft green landscape.
3) Hillstream Boulder Run
– Tank: 90 liters or larger, strong flow, high oxygen.
– Hardscape: Smooth boulders stacked to create a current path and resting zones. Build a river manifold or add powerheads aimed along the length of the tank.
– Plants: Willow moss and java moss on stones, anubias nana tucked in crevices, bolbitis in calmer eddies.
– Substrate: Sand and rounded pebbles to mimic a stream bed.
– Care: Cooler water around 20°C, vigorous surface agitation, and bright, clean stonework. Hillstream loaches will graze the biofilm and show natural behavior.
Livestock Add-Ons and Compatibility
Snails and Shrimp
Nerite snails handle cooler water and are excellent algae grazers. Ramshorn and bladder snails also do well and help clean up. For shrimp, Neocaridina and Amano shrimp are comfortable at 18–24°C, but avoid temps under 18°C for long periods. Do not mix shrimp with goldfish—they will be eaten.
Mixing Species
Keep fish that share similar temperature and flow needs. Do not mix goldfish with small, delicate community fish. Hillstream loaches need high flow that some other species will dislike. Always research each species’ requirements and temperament before combining.
Troubleshooting and Common Mistakes
Plants Melting in Cold Water
Some plants “melt” when moved, especially crypts. In cool tanks, this can be more noticeable because regrowth is slow. Do not panic. Keep the roots in place, reduce light slightly, and wait 2–4 weeks. New leaves usually appear once the plant settles.
Fish Uprooting Plants
Goldfish and some loaches love to dig. Use potted plants, heavy stones around the base, or switch to epiphytes that you can glue to hardscape. For rooted plants, plant deeper and weigh them down initially. Avoid delicate carpets with notorious diggers.
Algae from Too Much Light
Cool tanks do not need intense lighting. If algae shows up, reduce to 6 hours daily, increase floating plants, and improve flow. Make sure nutrients are balanced—zero nitrates can stunt plants; extremely high nitrates feed algae. Aim for 5–20 ppm nitrate and near-zero phosphate spikes.
Summer Heat Spikes
Sudden warm weather can push “coldwater” tanks into the upper 20s°C. Use fans, lift the lid for ventilation, add an air stone, and dim lights. Freeze water bottles and float them in a bag for emergencies, but avoid drops larger than 2°C in an hour. Plan ahead when heatwaves are forecast.
Cloudy Water and Bacterial Blooms
Cool water slows nitrifying bacteria. If you see a white haze, test ammonia and nitrite. Reduce feeding, increase aeration, and perform partial water changes until the filter catches up. Patience and stable routines solve most blooms.
Simple Care Schedule You Can Follow
Weekly
– 30–50 percent water change.
– Light gravel vac where detritus collects.
– Trim fast growers; thin floaters.
– Wipe glass and check filter flow.
Monthly
– Rinse filter media in old tank water.
– Add root tabs if needed.
– Re-glue any loose epiphytes.
Quarterly
– Evaluate the layout: open up crowded spots, refresh the foreground, and re-balance hardscape if the look has shifted.
Quick Purchasing Checklist
Essentials
– Tank with lid, full-spectrum LED, timer.
– Filter sized for 5–8x turnover (more for goldfish).
– Substrate suited to your fish and plants.
– Rocks and wood, cyanoacrylate gel, plant weights.
– Water test kit (ammonia, nitrite, nitrate, pH, GH/KH).
– Dechlorinator, small siphon, aquascaping tweezers and scissors.
Optional
– Air pump and stone for hot days or extra oxygen.
– CO2 kit for advanced growth.
– Root tabs and gentle liquid fertilizer.
– Clip-on fan for cooling.
Frequently Asked Practical Questions
Do I need a heater?
Usually not for 18–22°C tanks if your room is stable. A small heater set around 18°C can prevent dips in winter.
Can I do a carpet in cold water?
True carpets are harder without warm temps and CO2. Try Sagittaria subulata or a low vallisneria “meadow” instead of delicate micro-carpets.
Will goldfish eat all my plants?
They often nibble soft leaves, but tough epiphytes like anubias and java fern usually survive. Float hornwort or fast growers as a “salad bar” to reduce nibbling on your centerpiece plants. Pot rooted plants and shield them with stones.
What about algae eaters?
Nerite snails are your best bet for cool tanks. Amano shrimp help in community setups but not with goldfish. Avoid warm-water algae eaters in cool tanks.
Putting It All Together
Build a Coldwater Aquascape That Lasts
Start with your fish and the temperature range your home supports. Choose hardy plants that enjoy cool water—anubias, java fern, mosses, vallisneria, sag, hornwort—and anchor them well. Keep the design clean and practical: open swimming areas, stable hardscape, and secure plant placement. Provide reliable filtration, steady lighting at 6–8 hours, and modest fertilization. Be patient. In cooler tanks, plants grow at a measured pace, so your scape will evolve slowly and stay stable longer.
Conclusion
Yes, you can aquascape a coldwater aquarium, and it can be every bit as beautiful as a tropical tank. Focus on species that match your temperature, design around your fish’s behavior, and use hardy, cool-tolerant plants. Keep the light modest, filtration strong, and maintenance steady. Whether you dream of a tranquil goldfish river, a wind-swept meadow for white clouds, or a high-oxygen boulder stream for hillstream loaches, a coldwater aquascape is a rewarding, beginner-friendly project that grows with you—slowly, gracefully, and with less fuss than you might expect.