--- type: species title: "Shubunkin Goldfish Care Guide: Tank, Pond, Diet & More" slug: "shubunkin-goldfish" category: "freshwater" scientificName: "Carassius auratus" subcategory: "Single-Tail Goldfish" lastUpdated: "2026-04-24" readingTime: 10 url: https://www.fishstores.org/species/shubunkin-goldfish --- # Shubunkin Goldfish Care Guide: Tank, Pond, Diet & More *Carassius auratus* Learn how to care for shubunkin goldfish — tank size, water params, diet, pond setup, and compatible tank mates. The shubunkin (*Carassius auratus*) is the calico-patterned, single-tail goldfish that bridges the gap between the streamlined common goldfish and the speckled fancy varieties. It carries the torpedo body and fast, athletic swimming style of a [comet goldfish](/species/comet-goldfish), but wears the blue, black, orange, and white nacreous patterning that most keepers associate with calico orandas. That combination — pond-hardy build, calico color, single-tail speed — has made it one of the most-requested goldfish in US fish stores, even though most beginners dramatically underestimate the space it needs as an adult. ## Species Overview Shubunkins are domesticated *Carassius auratus* developed in Japan in the early 1900s by crossing calico telescope-eyed goldfish with single-tail commons. The result is a fish that breeds true for calico patterning over a slim, fast-swimming body. They are not a wild species; every shubunkin sold today traces back to a breeding line, with three distinct lineages — London, American, and Bristol — recognized by serious keepers. Pond keepers value them for hardy color; aquarists value them for their active personality. Both audiences regularly hit the same wall: an adult shubunkin is a 10-inch fish that needs serious horizontal swimming space. | Field | Value | | ----------------- | ------------------------ | | Adult size | 10-14 in (25-36 cm) | | Lifespan | 10-15 years | | Min tank (indoor) | 75 gallons (1 fish) | | Pond minimum | 250 gallons, 24+ in deep | | Temperature | 65-72 degrees F | | Difficulty | Beginner | ### Shubunkin Varieties — London, Bristol, and American The three shubunkin lineages share calico color but differ sharply in fin shape and overall profile. **London shubunkins** are the most common type sold in US fish stores. They have a stocky, common-goldfish body with short, rounded fins and a single, modestly forked tail. They are the hardiest of the three, the easiest to source, and the variety most often used in mixed-stock pond builds. **Bristol shubunkins** are the showpiece. They carry a long, deeply forked, lobed tail that fans into a pronounced "B-shape" when viewed from behind, with rounded tips that distinguish a true Bristol from a sloppy comet cross. The Bristol Aquarists Society in England maintains the breed standard, and quality Bristols remain rare outside of specialty importers and hobbyist breeders. **American shubunkins** sit between the other two — slightly longer fins than a London, less elaborate than a Bristol, with a tail that is forked but not lobed. American lines are essentially what most US backyard breeders produce when crossing calico stock without strict breed-standard selection. > **London, American, and Bristol — what to expect at your LFS** > > Most US fish stores carry London shubunkins under the generic label "shubunkin." American shubunkins show up at independent shops with stronger goldfish programs. True Bristol shubunkins are rare — if you see one at a chain pet store, it is almost certainly a mislabeled comet or American variety. Specialty pond-fish suppliers (Blackwater Creek Koi Farms, Hanover Koi Farms) carry verified Bristol stock seasonally. ### Size and Lifespan Shubunkins commonly reach 10 to 12 inches in a 75+ gallon tank, and 12 to 14 inches in a properly sized pond, within 3 to 5 years. They keep growing slowly throughout life, with exceptional pond specimens documented past 14 inches. Stunting is the most common reason a pet-store shubunkin tops out at 5 or 6 inches — a 20-gallon tank physically cannot grow this fish to its potential. Lifespan is 10 to 15 years with proper care. Pond-kept specimens routinely cross 15 years, and individual fish have been documented past 20 in stable, well-maintained ponds. Lifespan is driven almost entirely by water quality, filtration capacity, and the size of the system during the first two years of growth. ### Temperament and Activity Level Shubunkins are active, social, and constantly on the move. They cruise the entire water column from substrate to surface, school loosely with conspecifics, and beg aggressively at feeding time. They are not aggressive toward tankmates — there is no fin nipping, no territorial behavior — but their feeding speed and constant movement means slower fish (especially fancies) get pushed out at meals. > **Do not house shubunkins with fancy goldfish** > > Shubunkins are dramatically faster, more aggressive at feeding, and more spatially demanding than any double-tail fancy. A shubunkin in a tank with orandas or ryukins will eat most of the food, harass the slower fish during feeding, and stress the entire fancy population through sheer activity level. Keep shubunkins with other single-tails (commons, comets, other shubunkins) only. ## Water Parameters and Tank/Pond Requirements Shubunkins are cold-water fish with a heavy bioload and a need for horizontal swimming space. Tank or pond decisions should account for all three. ### Ideal Water Parameters Shubunkins thrive at 65 to 72 degrees F, with brief tolerance from 40 to 78 degrees. They are one of the most temperature-resilient ornamental species sold — the same fish can overwinter under ice in a deep pond and acclimate to summer water in the high 70s. They do not need a heater in any normal US household, and a tropical-tank thermostat (76+ degrees F) actively shortens their lifespan. Target pH 7.0 to 7.4 with general hardness between 5 and 19 dGH. Goldfish tolerate moderately alkaline, hard water exceptionally well. Ammonia and nitrite must read 0 ppm at all times; both damage gill tissue at any detectable level. Keep nitrate below 20 ppm with weekly 25 to 30 percent water changes on indoor tanks; pond keepers should aim for the same nitrate ceiling but achieve it through a combination of plant uptake, larger water volumes, and seasonal water changes. ### Minimum Tank Size and Filtration A single shubunkin needs a 75-gallon tank as the practical indoor minimum, with 20 gallons added per additional fish. A pair needs 95+ gallons; a group of four needs 135+ gallons. The fancy-goldfish community has shifted upward on tank-size recommendations over the last decade as the negative effects of stunting have become better documented, and shubunkins — which grow larger than most fancies — sit at the high end of that recommendation curve. Long, wide tanks dramatically outperform tall designs. A 75-gallon standard (48 by 18 by 21 inches) gives a shubunkin the horizontal sprint room it needs; a 75-gallon column does not. Use the [aquarium dimensions guide](/guides/aquarium-dimensions) to compare footprint options before you buy. Filtration should turn over the tank volume at least 8 to 10 times per hour. For a 75-gallon tank, that means combined filtration rated for 600 to 750 GPH. Canister filters (Fluval FX series, Oase BioMaster) and oversized hang-on-back units handle the bioload well. Surface agitation is also important — a return spray bar or air stone keeps dissolved oxygen high enough to support the heavy gill workload. ### Pond Suitability Shubunkins are first and foremost pond fish. Indoor tanks work, but the species genuinely thrives outdoors with the room to grow, the temperature variation that mimics natural seasonal cycles, and the natural food sources a pond ecosystem provides. The minimum pond is 250 gallons with at least 24 inches of depth — depth is critical for winter survival, since the deep zone gives the fish a thermal refuge below the ice line. In USDA hardiness zones 5 through 9, shubunkins overwinter outdoors successfully if the pond does not freeze solid. A floating de-icer or air stone keeps a hole open in the ice for gas exchange, which is the single most important winter intervention. Stop feeding when water temperatures drop below 50 degrees F. The fish's metabolism slows dramatically, and undigested food rots in the gut, polluting the water and stressing the immune system. Resume feeding gradually as spring temperatures rise above 55 degrees F consistently. ### Aquascape and Substrate Smooth substrate only. Sharp gravel scrapes the fish during normal foraging. Acceptable options include polished river gravel (under 3 mm or over 8 mm — the in-between size lodges in the mouth), pool filter sand, or a bare bottom for indoor tanks where easy siphoning matters. Shubunkins uproot live plants relentlessly and snack on tender leaves. Keepers who want planted goldfish tanks have three workable options: tough-leaved species (anubias, java fern, large amazon swords) anchored to driftwood or rock; potted plants kept in small terracotta pots that the fish cannot upend; or quality silk plants. Avoid delicate stem plants — the fish will shred them within a week. ## Diet and Feeding Diet drives swim bladder health, color, and growth. Get this right and you prevent the most common shubunkin problems before they start. ### Staple Foods and Feeding Frequency Sinking pellets should be the daily staple. Floating pellets force the fish to gulp at the surface, ingesting air that contributes to swim bladder problems. Look for sinking pellets with high protein (35 to 40 percent) and added spirulina or astaxanthin for color enhancement — Hikari Goldfish Staple, Saki-Hikari, and Repashy Super Gold are widely used by goldfish keepers. Feed 2 small meals per day, offering only what the fish can consume in about 2 minutes per session. Shubunkins are perpetually hungry and will beg convincingly at the glass — ignore them. Overfeeding is far more dangerous than underfeeding for any goldfish, and especially for indoor shubunkins where the bioload is concentrated in a smaller volume. ### Supplemental Foods Blanched vegetables belong in the rotation 1 to 2 times per week. De-shelled peas, blanched zucchini slices, and blanched spinach all provide fiber that keeps the goldfish digestive tract moving. Peas in particular are the classic remedy for a constipated or floating shubunkin. Live and frozen foods — daphnia, brine shrimp, bloodworms, and chopped earthworms — work as treats once or twice a week. Daphnia is especially useful because the chitin exoskeleton acts as digestive roughage. Pond-kept shubunkins also forage natural insect larvae, algae, and small invertebrates, which reduces (but does not eliminate) the need for supplemental feeding. ### Avoiding Overfeeding and Swim Bladder Issues Shubunkins are less swim-bladder-prone than fancies because their elongated body does not compress the organ the way a deep-bodied fancy frame does. They are not, however, immune. Overfeeding, gulping air at the surface, and constipation from low-fiber diets all trigger swim bladder symptoms — typically a fish floating sideways or sinking nose-down. Fast the fish one day per week. A weekly fast clears partially digested food from the gut and gives the swim bladder a chance to reset. Most experienced shubunkin keepers fast on the day before a water change, which keeps the cleanup routine simple. ## Tank Mates and Compatibility Shubunkins are peaceful but fast-moving and aggressive at feeding time. Compatible tankmate selection comes down to matching speed, temperature preference, and size. ### Best Companions Other single-tail goldfish are the natural choice. [Common goldfish](/species/common-goldfish), [comet goldfish](/species/comet-goldfish), and other shubunkins all share the same body shape, swimming speed, temperature range, and feeding style. A pond or tank stocked entirely with single-tail varieties is the closest thing to a no-conflict goldfish setup. Beyond goldfish, dojo loaches (weather loaches, *Misgurnus anguillicaudatus*) are the classic compatible species. They tolerate cold water, are peaceful, and occupy the bottom of the tank where shubunkins spend less time. Hillstream loaches and white cloud mountain minnows can also work in cooler indoor tanks. For ponds, native pond snails and freshwater mussels coexist well with shubunkins without becoming snacks. ### Species to Avoid Fancy goldfish (orandas, ryukins, ranchus, telescopes, pearlscales) are the wrong call. The speed mismatch causes fancies to lose at every feeding, and the constant activity stresses slower fish over time. The [fancy goldfish care guide](/guides/fancy-goldfish-guide) covers the why in more depth — this is the most consistently violated compatibility rule in the goldfish hobby. Tropical fish are also incompatible. Their preferred temperature range (76 to 82 degrees F) is significantly higher than the shubunkin's, and trying to compromise at 74 degrees stresses both groups long-term. The [freshwater fish overview](/guides/freshwater-fish) covers temperature compatibility in more depth. Small invertebrates (cherry shrimp, small ramshorn snails) become snacks. Fin nippers (tiger barbs, serpae tetras) shred the long shubunkin caudal fin. Aggressive cichlids and large predatory fish are obvious mismatches. ### Pond Cohabitation Shubunkins coexist with koi if size and pond capacity match. A 5-inch shubunkin in a pond with 18-inch koi will lose at every feeding — koi simply outcompete smaller fish for food. The general guideline: keep shubunkins and koi within 2 to 3 inches of each other in length, and stock the pond at 500+ gallons with separate feeding zones if possible. Avoid stocking shubunkins with smaller pond species (rosy red minnows, mosquitofish) that they will outcompete or eventually eat. Conversely, never house shubunkins with predatory pond fish (largemouth bass, catfish) — shubunkins are slow enough to be lunch. ## Breeding Shubunkin Goldfish Shubunkins breed readily in ponds and occasionally in large tanks. Production-quality breeding for color and finnage selection is a different commitment than casual spawning. ### Sexing and Spawning Triggers Mature shubunkins (2+ years) are sexable during breeding season. Males develop small white tubercles (breeding stars) on the gill covers and leading edges of the pectoral fins — they look like tiny white salt grains. Females become noticeably rounder when carrying eggs, with a slight asymmetry visible from above as the body fills out. Spawning is triggered by a winter cool-down followed by a spring warm-up. In ponds, this happens naturally — the temperature drops near 50 degrees F over winter, then climbs through spring, triggering males to chase females through plants and spawning mops. In tanks, you can mimic the cycle by lowering temperature to 50 to 55 degrees F for several weeks, then warming gradually to 68 to 72 degrees F over a week or two. ### Egg Care and Fry Survival Shubunkins are egg-scatterers. Females release several thousand sticky eggs across plants, spawning mops, or pond vegetation, which males fertilize immediately. Adults will eat the eggs within hours if not separated, so move the spawning substrate to a dedicated hatching tank as soon as spawning ends. Eggs hatch in 4 to 7 days at 70 degrees F. Fry are tiny and need infusoria or commercial liquid fry food for the first week, then progress to baby brine shrimp and crushed flake. Calico color does not develop until the 3 to 6 month range — fry start out solid bronze, and the calico patterning emerges as scales mature. Quality breeders wait 6 to 12 months before culling for color, body shape, and finnage. ## Common Health Issues Most shubunkin diseases trace back to one root cause: poor water quality. Fix the water first, then address symptoms. ### Ich and External Parasites **Ich** (*Ichthyophthirius multifiliis*) presents as white salt-grain spots on the body and fins, often paired with flashing (rubbing against decor) and clamped fins. Treatment in cold water requires a longer cycle than in tropical tanks because the parasite life cycle slows at lower temperatures. The standard protocol: gradually raise tank temperature to 78 degrees F over 2 to 3 days, dose aquarium salt at 1 tablespoon per 5 gallons, and complete a full 14-day treatment cycle to break the parasite life cycle. Pond treatment is more complex because heating an outdoor pond is impractical — extended salt treatment (0.3 percent salinity for 3 to 4 weeks) and commercial pond ich medications are the typical approach. ### Swim Bladder Disorder Shubunkins are less swim-bladder-prone than fancies, but not immune. Symptoms include floating sideways, sinking nose-down, or swimming in tight loops. Causes are usually overfeeding, constipation from low-fiber diets, or gulping air at the surface during flake feeding. Treatment: fast the fish for 24 to 48 hours, then offer a skinned, blanched pea (the fiber gets the digestive tract moving). Switch permanently to sinking pellets to eliminate air ingestion. If symptoms persist beyond 4 to 5 days, bacterial infection of the swim bladder may be the underlying cause — a course of broad-spectrum antibiotics (Maracyn 2, Kanaplex) is the next step. ### Fin Rot and Bacterial Infections **Fin rot** appears as ragged, fraying fin edges, often with a white or red margin. It is almost always caused by poor water quality, a recent injury, or chronic stress. Long Bristol shubunkin caudal fins are especially prone because their length increases the surface area exposed to bacterial colonization. Fix the water parameters first — a 50 percent water change immediately — then treat with aquarium salt (1 tablespoon per 5 gallons in a hospital tank) for mild cases or a broad-spectrum antibiotic if the rot does not improve within a week. Prevention through clean water beats treatment every time. ## Where to Buy and What to Look For Healthy shubunkins start with a healthy source. Where you buy matters as much as what you buy. ### Selecting Healthy Fish at Your Local Fish Store Visit the store, observe the shubunkin tank for at least 5 to 10 minutes, and run through this checklist before asking staff to bag anything: ### Healthy Shubunkin Checklist - [ ] Active, upright swimming throughout the water column — no listing, no bottom-sitting - [ ] Clear, bright eyes with no cloudiness or swelling - [ ] Intact, unfrayed fins with no ragged edges, white spots, or red streaks - [ ] Smooth, flat scales — no raised scales (raised scales indicate dropsy, often fatal) - [ ] Calico patterning that looks vibrant, not faded — blue base coloration is a quality marker - [ ] No flashing or scratching against decor or substrate - [ ] Tank water is clean and clear with no ammonia smell - [ ] No dead or visibly sick fish in the same tank or shared filtration system > **The blue base color is the single best quality marker** > > A quality shubunkin shows a clear blue or blue-grey base color underneath the orange, black, and white spots. That blue base develops only in fish from quality nacreous-scale bloodlines, and it is the visible difference between a top-tier shubunkin and a generic calico goldfish mislabeled as one. If the base color is washed-out white or pure orange, you are looking at a low-grade or mislabeled fish. Ask staff how long the fish have been in the store (newly arrived shipments are still stressed), whether new arrivals are quarantined, and what the fish are currently being fed. A knowledgeable shop will answer confidently. Vague answers are a red flag. ### Price Range and Varieties Available London shubunkins are the most widely available and the cheapest — expect $5 to $15 at most chain pet stores and independent fish shops. American shubunkins typically run $10 to $25 at independents, slightly more for larger or better-colored specimens. Bristol shubunkins are rarer and command premium prices: $30 to $80+ for show-quality specimens from specialty importers, with seasonal availability. For a first shubunkin, a healthy $10 London from a clean local shop will bring more lasting joy than a $80 Bristol that arrives stressed from overnight shipping. Save the import-quality breeders for your second or third fish, when you have established water and a working quarantine routine. Acclimation should be drip-style over 60 to 90 minutes for shipped fish, or float-and-add over 30 minutes for short-distance LFS purchases. Always use a quarantine tank for 2 to 4 weeks before adding a new shubunkin to an established display or pond. ## Quick Reference - **Adult size:** 10-14 inches in proper tank or pond conditions - **Tank size (indoor):** 75 gallons for one fish, +20 gallons per additional fish - **Pond minimum:** 250 gallons, 24+ inches deep for winter hardiness - **Temperature:** 65-72 degrees F (no heater needed; tolerates 40-78 degrees seasonally) - **pH:** 7.0-7.4 | **Hardness:** 5-19 dGH - **Ammonia/Nitrite:** 0 ppm | **Nitrate:** under 20 ppm - **Filtration:** 8-10x tank volume per hour, surface agitation for oxygen - **Substrate:** Smooth river gravel, sand, or bare bottom — never sharp gravel - **Diet:** Sinking pellets (staple), blanched vegetables, occasional frozen treats - **Feeding:** 2 small meals daily, 2-minute rule, fast one day per week - **Tankmates:** Other single-tail goldfish (commons, comets, other shubunkins), dojo loaches, similar-sized koi in ponds - **Avoid:** Fancy goldfish, tropical fish, fin nippers, undersized tanks, sharp decor - **Lifespan:** 10-15 years (some pond-kept specimens past 20) - **Varieties:** London (most common), American (mid-tier), Bristol (rare, lobed tail) - **Quarantine:** 2-4 weeks for every new fish, no exceptions For variety comparisons across the broader goldfish family, see the [fancy goldfish care guide](/guides/fancy-goldfish-guide) — which is also the canonical reference for why fancies and shubunkins should never share a tank. ## Frequently Asked Questions ### How big do shubunkin goldfish get? Shubunkins typically reach 9-12 inches in a properly sized tank or pond. In small tanks their growth is stunted, which harms long-term health. Pond-kept shubunkins often reach the upper end of that range within 3-5 years. ### Can shubunkin goldfish live in a tank indoors? Yes, but they need at least 75 gallons for one fish. They produce heavy waste, so robust filtration is essential. Many keepers ultimately move shubunkins to outdoor ponds as they grow. ### What is the difference between London and Bristol shubunkins? London shubunkins have small, rounded fins; Bristol shubunkins have large, well-developed lobed tail fins. American shubunkins fall between the two. Bristol types are rarer in US fish stores. ### Can shubunkin goldfish live with koi? Yes, if size is comparable and the pond is large enough (500+ gallons recommended). Koi can outcompete smaller shubunkins for food, so monitor feeding carefully and ensure both species are similar in size. ### How long do shubunkin goldfish live? With good water quality and diet, shubunkins commonly live 10-15 years. Some pond-kept specimens have exceeded 20 years. Lifespan is heavily influenced by tank size, filtration quality, and consistent water changes. --- *Source: [FishStores.org](https://www.fishstores.org/species/shubunkin-goldfish)* *Last updated: April 24, 2026*