Freshwater Fish · Loaches
Dojo Loach
Misgurnus anguillicaudatus
Storm-sensing coldwater loach with puppy-dog charmIntermediate
- Lifespan
- 7-10 years; 15+ documented in cool ponds
- Size
- 15-25 cm (6-10 in); up to ~30 cm (12 in)
- Social needs
- Social - keep 3+ together (5+ better)
- Time
- Moderate (daily feed, weekly water changes)
- Cost
- Medium (cheap fish, large tank)
- Diet
- Omnivore (bottom-feeder, sinking foods)
Overview
What is this animal?
- The Dojo Loach, also sold as the weather or pond loach, is a thick-bodied, eel-shaped East Asian loach that comes in a mottled brown wild form and a popular golden morph.
- Its defining party trick is weather-sensing: a drop in barometric pressure before a storm sends the whole group darting and spiralling around the tank, which earned it the weatherfish name.
- Unlike the site's other loach, the small and secretive Kuhli, the Dojo is a bold, out-in-the-open fish that commonly reaches 15-25 cm (6-10 in) and can top 30 cm (12 in), and it actively interacts with its keeper, often learning to feed from the hand.
- Its intermediate rating reflects the space a full-grown group needs and its temperate-water requirements, not any fragility.
- One serious caveat comes before purchase: this species is highly invasive when released, and keeping it is prohibited or restricted in several US states (Michigan, Minnesota, and Oregon among them) and other countries.
- Check your local laws before buying, and never release an unwanted fish into any waterway.
Temperament
- Dojo Loaches are peaceful, tactile, and genuinely social, resting in piles and following each other around the tank.
- Keep at least three together, and ideally five or more, because a solitary Dojo becomes listless and hides far more.
- They are among the most interactive freshwater fish, approaching the glass when their keeper appears and often tolerating a gentle touch at feeding time, which is why keepers call them the puppies of the fish world.
- This boldness makes them a daytime centrepiece rather than a fish you glimpse after lights-out.
- Match them only with other temperate species, with goldfish, White Cloud Mountain Minnows, and Zebra Danios being the classic companions.
- They ignore tankmates they cannot swallow, but dwarf shrimp and very small fish may disappear overnight, and tropical communities are the wrong home for temperature reasons alone.
A good fit for
- Unheated, temperate aquariums and coldwater ponds
- Companions for goldfish, White Clouds, and other coldwater fish
- Keepers wanting an interactive, hand-tame fish
- Soft sand-bottom tanks with a 4ft-plus footprint
- Snail control in coldwater tanks
Common mistakes to avoid
- Sustained warmth over ~25C (77F) shortens their lives
- Undersized tanks; a trio needs ~75gal / 4ft+, adults reach 30cm (12 in)
- Any unsealed lid gap (expert climbers and jumpers)
- Restricted or banned in some regions; check laws, never release
- Salt, copper, and full-strength medications harm their thin scales and slime coat
- Keeping one alone instead of a group of 3+
Enclosure
Minimum 280 litres (74 US gallons) — for a group of 3
Cannot be kept alone. The minimum is 3, and the space above is for that group.
- Dojo Loaches are temperate fish, not tropical, and do best at 15-23C (59-73F) in an unheated tank in a normal room, with the mid-60s F being the sweet spot for active behaviour and longevity.
- Sustained temperatures above about 25C (77F) raise their metabolism, stress their immune system, and measurably shorten their lives, which is the most common way keepers get this species wrong.
- A group of three adults needs at least about 280 litres (75 gallons) with a 4ft-plus (120cm) footprint, and a 6ft tank better suits a full-grown group, because these are large, active, substrate-length fish that swim hard when the pressure drops.
- Provide several centimetres of soft sand so they can bury themselves with just the head showing, which is natural resting behaviour and impossible on gravel.
- They are intestinal breathers that gulp air at the surface, and they are legendary escape artists that climb airline tubing and squeeze past filter cut-outs.
- A tightly fitted, weighted lid with every gap sealed is non-negotiable, and the tank must be fully cycled with pH 6.5-8.0 and weekly 30% water changes.
Supplies
Setup
- Tank and stand
- Filter
- Heater and thermometer
- Substrate, plants and decor
- Liquid test kit
- Dechlorinator and starter supplies
Ongoing
- Sinking wafers and tablets
- Frozen bloodworm, daphnia and brine shrimp
- Live blackworms (optional, from a clean source)
- Fine sand substrate
- Turkey baster or pipette for target-feeding the bottom
- Feeding tongs
- Fine net for removing leftovers
Safe substrate: Inert aquarium gravel · Fine, smooth sand · Aquasoil for planted tanks
Care routine
Daily
- Check temperature and equipment
- Feed
- Head-count and look everyone over
Weekly
- Top up evaporationevery 3 days
- Clean glass and clear algae
- Head-count with a torch
- Test the water
- Water change and gravel vacuum
Monthly
- Check the substrate stays softevery 2 weeks
- Trim and thin the plantsevery 2 weeks
- Check supplies and reagent dates
- Review medication doses
- Rinse the filter media
Less often
- Replace chemical filter media (Carbon/Purigen)every 2 months
Vet: Quarterly head-count and substrate review — every 3 months
Top resources for more info
Independent creators and organisations we would send a friend to. We have no affiliation with any of them, and nothing here is sponsored. Links checked 2026-09-19.
YouTubers
Girl Talks FishCare how-tos by fish type, tank setup and beginner mistakesAquarium Co-OpSpecies care guides, filtration and fish health (run by a retailer)Prime Time AquaticsSpecies profiles, stocking and water chemistry explained plainly
Sites
Go deeper
Diet
- Dojo Loaches are greedy bottom-feeding omnivores that take almost anything reaching the substrate.
- Feed sinking pellets and wafers as the staple, plus frozen or live bloodworm, blackworm, and brine shrimp, and occasional blanched vegetables such as cucumber and courgette.
- They will happily eat small aquarium snails, which makes them useful in snail-plagued temperate tanks.
- Many settle in well enough to wriggle up and take food directly from their keeper's fingers.
- Their appetite is their weakness, and an unmeasured feeder will produce an obese loach in months.
- Offer only what the group clears in a few minutes once or twice daily, and make sure food actually reaches them if faster surface-feeders like goldfish share the tank.
Health
- Dojo Loaches are hardy in cool, clean water, and most health problems trace back to being kept too warm or in an immature tank.
- Like other loaches they have tiny embedded scales and a sensitive slime coat, so salt, copper, and full-strength medications must be avoided or dosed at reduced strength.
- Red blotch disease, showing as inflamed red patches on the belly and flanks, is strongly associated with this species when it is kept warm or in poor water, and it needs prompt cooling, pristine water, and veterinary-guided antibacterial treatment.
- Newly imported, farm-raised stock frequently carries internal parasites, so quarantine new fish for 4 weeks and watch for a fish that eats well yet stays thin.
- Their intestinal breathing lets an escapee survive on the floor for a surprisingly long time, but many are still lost this way.
- Check the lid after every feed, and return any found jumper to the tank promptly, as it may well recover.
Is your enclosure big enough?
Minimum volume280 litres (74 US gallons)
Swimming length122 cm minimum. A tall tank of the right volume is still the wrong shape.
CompanyCannot be kept alone. The minimum is 3, and the space above is for that group.
Is this urgent?
In a fish tank the patient is usually the water. Test before you treat — dosing a healthy tank for a disease it does not have makes things worse.
Go now
Any detectable ammonia or nitrite in a stocked tankLarge water change now with dechlorinated, temperature-matched water. Stop feeding. Test again in 12 hours. Both are directly toxic. How toxic the ammonia reading is depends on pH and temperature, so the same number can be harmless or lethal.
NowFish gasping at the surface, or crowding the filter outflowIncrease surface agitation immediately, then test the water. Either the oxygen has crashed or the gills are being chemically burned. Both are hours-scale problems.
NowSudden deaths, more than one fish in a dayTest ammonia, nitrite, nitrate and temperature before doing anything else. Do not add medication yet. Multiple simultaneous deaths point at the water or the equipment, not at a pathogen.
NowToday
Flashing — repeatedly scraping against decor or substrateTest the water, then look closely for parasites. Irritation is either chemical or parasitic; the test tells you which before you medicate.
TodayWhite salt-grain spots over the body and finsBegin the appropriate treatment today and check the temperature. The parasite's life cycle is temperature-driven, and it multiplies with every cycle you wait.
TodaySoon
Clamped fins, hiding, or refusing food for more than two daysTest the water and review recent changes. Usually the earliest visible sign of a parameter drifting.
A few daysNever add a new fish to a tank that is not fully cycled, and never treat blind. A test kit is cheaper than the fish.
This is general guidance for a healthy adult, not a diagnosis. An exotics vet who knows your animal always overrides it — and the time to find one is before you need one.
What it really costs
Setup, monthly, first year and across a whole life, itemised and with the electricity worked out from the actual wattage. Published figures for the same animal disagree by a factor of four, so the calculator shows ranges rather than picking one.
Bedding and substrate
Substrate in an aquarium is a filter as much as a floor. Most of the biology lives in and on it.
Safe
Inert aquarium gravelRinse thoroughly before use. Grain size should be too large to swallow and too small to trap food.
safeFine, smooth sandCorrect for corydoras, kuhli loaches and anything that sifts. Their barbels wear away on sharp gravel.
safeAquasoil for planted tanksExcellent for plants, but it leaches ammonia for the first weeks. Cycle around it; do not stock into it.
safeBare bottomLegitimate for quarantine and grow-out tanks. Easy to clean, but it holds far less biological filtration.
safeWith a caveat
Crushed coral or aragoniteDeliberately raises hardness and pH. Correct for rift-lake cichlids, wrong for soft-water species.
with a caveatVery deep sand bedsAnaerobic pockets form below about 5 cm in still sand. Either keep it shallow or keep it stirred.
with a caveatPainted or coated gravelUsually fine, but coatings chip. Test a handful in a jar for a week first.
with a caveatNever
Sharp or angular gravel with bottom-dwellersWears down barbels and leads to infection in corydoras and loaches.
neverAnything containing metal, limestone of unknown origin, or shells in a soft-water tankSlowly alters chemistry in ways that are hard to diagnose later.
neverThis is our general list for freshwater fish. We have not built one specific to Loaches yet.
My kit says 0.25 ppm. Is that dangerous?
A liquid kit measures total ammonia, but only the un-ionised fraction is really toxic, and that fraction is governed by pH and temperature — each whole pH unit multiplies it roughly tenfold. So the same reading can be nearly harmless in one tank and lethal in another; this works out which one you are in.
Compare with other animals
The same axes for every animal, side by side — the way the guides are written makes that a fair comparison rather than two articles.
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Loaches, side by side
Same axes, same care guides — the honest way to choose between types.
See all Loaches side by side →
