Easy to intermediate
Chocolate Cherry Shrimp (Neocaridina davidi)
18–26°C · pH 6.5–8 · 30L
£13.99
One unsexed Marbled Hillstream Loach per quantity at the supplier's approximate 3-4 cm dispatch size. A surface-oriented Sewellia marmorata for mature 80-litre-or-larger aquariums with high oxygen and varied flow.
Sewellia marmorata
Marbled Hillstream Loach are a shoaling species — they need 6+ to feel safe and show their full colour. Larger shoals stay calmer, eat better, and look stunning.
Confirm your email, then we’ll send an availability message for this exact item if it returns within 180 days.
This request is only for this product—no newsletter or other promotions. A mail-provider retry may very rarely duplicate the same availability message. Unconfirmed addresses are removed after 48 hours. See our privacy policy.
One unsexed Marbled Hillstream Loach per quantity at the supplier's approximate 3-4 cm dispatch size. A surface-oriented Sewellia marmorata for mature 80-litre-or-larger aquariums with high oxygen and varied flow.
18–26°C · pH 6.5–8 · 30L
23–27°C · pH 7.4–8.4 · 1000L
20–24°C · pH 7–8 · 45L
24–28°C · pH 5.5–7 · 60L
Maintain these water conditions for optimal health and vibrant colors
Marbled Hillstream Loach is the practical aquarium-trade name used here for Sewellia marmorata, a small, flattened freshwater loach from central Vietnam. Each quantity adds one unsexed fish at the supplier's approximate 3-4 cm dispatch size. That size is a variable supplier band, not a promise of an exact measurement and not the adult size.
This is a specialist-shaped fish for a mature aquarium with clean, highly oxygenated water, stable chemistry and broad surfaces to explore. It is not an automatic algae solution and should never be bought to clean an immature tank. FishBase records aquatic invertebrates in the stomach contents of wild S. marmorata, while UK ornamental-fish guidance recommends a varied sinking diet and established grazing surfaces for hillstream loaches.
The species-level habitat evidence is more nuanced than the usual "maximum current everywhere" advice. S. marmorata has been collected around shallow rapids with clear water and relatively slow current, as well as deeper pools with detritus and muddy or sandy substrate. In an aquarium, provide excellent oxygenation and purposeful circulation while also creating calmer resting pockets. Do not force the fish to spend every moment directly in front of a powerhead.
A practical starting point is an aquarium of at least 80 litres for a small group of three or four, following OATA's hillstream-loach guidance. Prioritise a long footprint, mature filtration, secure cover, rounded stones, smooth cobbles, sand or fine smooth gravel, and several feeding stations. A single fish from this listing is most appropriate when it will join an established compatible group, not as a permanently solitary display animal.
"Marbled Hillstream Loach" is a trade label rather than an official English name recorded by FishBase. The scientific identity on this page follows the supplier record, Sewellia / marmorata. The supplier does not provide a collection locality, sex, age, or wild-caught versus captive-bred status, so this listing does not invent any of those details.
| Care point | Practical target | Why it matters |
|---|---|---|
| Adult size | Up to about 5.9 cm standard length | The temporary 3-4 cm dispatch band must not be used for adult planning |
| Group | At least 3-4 compatible hillstream loaches | OATA advises a small group; provide several resting and feeding surfaces |
| Aquarium | 80 L+ with a long footprint | Gives the group stable water, horizontal territory and varied flow zones |
| Temperature | 18-24°C | Matches OATA's hillstream-loach range; oxygen management becomes more important near the warm end |
| pH | 6.5-8.0 | Stability and a careful match to source water matter more than chasing one exact value |
| Hardness | 4-12 dGH; 3-10 dKH | A broad soft-to-medium range allows a sensible water match without abrupt chemical adjustment |
| Water quality | 0 ammonia; 0 nitrite; low nitrate | Clean water and dependable biological filtration are core welfare requirements |
| Flow and oxygen | High oxygen, purposeful flow and calmer pockets | The fish needs well-aerated water but should be able to choose its position |
| Diet | Varied sinking foods with small invertebrate foods | Natural stomach evidence does not support treating this species as an algae-only grazer |
| Tank region | Bottom, stones, wood, glass and other solid surfaces | Its flattened body and paired fins are adapted for close contact with surfaces |
These are home-aquarium planning targets, not instructions to change a new arrival rapidly to ideal-looking numbers. Test both systems before purchase and compare the actual readings. Our water matcher helps organise temperature, pH and hardness differences so the arrival plan reflects the water in front of you.
Sewellia marmorata was described by Serov in 1996 and is currently accepted in the family Gastromyzontidae. The family contains the highly flattened loaches commonly grouped under the hillstream-loach name. Their broad paired fins and flattened head and body help them maintain contact with solid surfaces in moving water. They are not plecos and are not closely related to South American suckermouth catfish.
FishBase places this species in the Vinh Thanh river catchment in Vietnam and gives a maximum published length of 5.9 cm standard length. Standard length stops at the base of the tail, so the whole fish can look slightly longer when the caudal fin is included. Use the adult figure for aquarium planning, not the size printed on a supplier stock list.
The English phrase "Marbled Hillstream Loach" is useful to customers because it describes both appearance and body type, but it should not be presented as a formal taxonomic name. FishBase does not list an English common name for this species. Other sellers may use names such as Fireworks Hillstream Loach or translated European names. Those labels are not evidence that the fish is a different subspecies, locality or captive line.
The sale identity follows Petra Aqua's current catalogue record, which names the fish Sewellia / marmorata and supplies a 3-4 cm size band. Species-level identification in Sewellia can be difficult from a single aquarium photograph because pattern, viewing angle, age and preservation all affect what can be seen, while some diagnostic features are on the mouth and fins. This page therefore records the supplier identification without claiming independent examination of the dispatched specimen.
If a customer is maintaining a conservation or breeding collection, visual similarity is not enough. Keep supplier records, avoid mixing uncertain Sewellia species, and obtain specialist identification before claiming a pure breeding line. For an ordinary display aquarium, the safe approach is still to plan around the welfare needs of a small, surface-oriented hillstream loach.
FishBase reports S. marmorata as Endangered from an IUCN assessment dated 2010, with a restricted central-Vietnam range and habitat decline among the concerns. This is not marketing language and the fish should not be promoted as "rare" simply to create urgency. The responsible response is accurate identification, good lifetime husbandry, traceable records where available and no release into British waterways.
The supplier has not stated whether this stock is wild-caught or captive-bred. The page must therefore say that origin is unknown rather than borrowing a claim from another retailer. Customers who need confirmed captive-bred stock should ask before ordering and wait for documented confirmation.
A true Sewellia has a broad, dorsoventrally flattened front half, a distinct head, wide pectoral and pelvic fins and a narrower tail section. Seen from above, the outline can resemble a small ray or butterfly. The mouth sits underneath the head, where specialised structures help the fish feed while remaining close to rock and other surfaces.
The supplier reference for this SKU shows a flattened fish with a dark marbled or reticulated pattern over a yellowish background. Individual markings are not printed templates. Contrast, line thickness, spots and broken markings can vary, and transport stress or aquarium lighting can change how strongly the pattern appears.
The existing gallery scenes are representative illustrative renders, not photographs of the exact fish that will be dispatched. They are retained as part of the established gallery and are not evidence of an individual's pattern, sex, maturity or body condition. The scientific identity and dispatch size come from the supplier record, not from reverse-identifying a rendered scene.
Use the gallery to understand the general aquarium subject, not to select one exact specimen. The fish delivered can differ in pattern, shade, proportions and size within the supplier band. No image on this page guarantees sex, collection locality, captive-bred origin or the pictured individual.
OATA recommends at least 80 litres for a small group of hillstream loaches. Volume alone is not enough: a tall cube may contain the same litres as a longer aquarium but provide much less usable surface area. Choose a long footprint where circulation can travel along the tank and where each fish can occupy a separate stone or feeding patch.
Plan for at least three or four compatible hillstream loaches. Add more space when combining species, retaining a larger group or introducing other bottom-oriented fish. The correct capacity depends on adult biomass, filtration, surface area, water quality and social behaviour, not a simple centimetres-per-litre formula.
Use sand or fine smooth gravel around rounded cobbles and broad smooth-edged stones. Check every rock for unstable stacking and sharp points before water is added. Position stones so waste can be siphoned and flow can pass around them without creating inaccessible dirt traps. Stable wood can add cover, but it should not reduce the open, oxygenated surface area the fish uses.
Mature surfaces matter because they carry microbial films, fine natural foods and familiar textures. Mature does not mean dirty. Keep the aquarium biologically established and allow some safe growth on selected stones or side panels while still removing trapped waste and uneaten food. Clean viewing glass does not require stripping every surface at once.
Plants are optional if the rest of the habitat is well planned, but sturdy species attached to wood or rock can add shade and visual barriers. Leave open stones under the light for natural surface growth. Protect plant roots from direct powerhead output and avoid decorations with rough mould seams that could damage a fish moving tightly across them.
Use a secure lid and cover cable or pipe gaps. A fish exploring the waterline can use wet glass and equipment as a route out. Escape attempts can also signal unsuitable water, crowding or stress, so do not treat a lid as a substitute for correcting the environment.
Use mature biological filtration sized for the full community. A powerhead, spray bar or circulation pump can create directional movement, but the intake must be guarded so a small fish cannot be trapped. Combine water movement with surface agitation or another dependable method of gas exchange. High turnover on a filter box does not automatically prove that oxygen reaches every part of the aquarium.
Build a flow gradient. One route can carry stronger current across exposed stones, while rocks and wood create lower-velocity pockets behind them. Watch where the fish chooses to rest and feed. If every animal is pinned into one sheltered corner, the display may have impressive pump output but poor usable habitat.
For this listing, use OATA's hillstream-loach range of 18-24°C as a practical framework. The current UK statutory guidance for sellers separately groups hillstream loaches at 17-23°C. These ranges overlap and both emphasise stable conditions. Choose a set point that every tank mate can share and that the room can maintain safely through summer and winter.
Warm water holds less dissolved oxygen than cooler water. A tank that is comfortable in winter can become marginal during a heatwave, particularly overnight when plants and microorganisms consume oxygen. Monitor temperature, increase safe surface movement when needed and have a cooling plan before the room becomes hot. Do not add cold water suddenly or create rapid temperature swings.
| Parameter | Working range | Practical check |
|---|---|---|
| Temperature | 18-24°C | Use a reliable thermometer and plan for warm weather |
| pH | 6.5-8.0 | Match source water where practical; avoid rapid chemical correction |
| General hardness | 4-12 dGH | Test the tap and aquarium rather than assuming "UK water" is one value |
| Carbonate hardness | 3-10 dKH | Track buffering where pH stability is a concern |
| Ammonia | 0 mg/l | Any detectable reading requires investigation and corrective action |
| Nitrite | 0 mg/l | Do not add the fish to an uncycled aquarium |
| Nitrate | No more than 20 mg/l above normal tap-water level under OATA guidance | Record trends and adjust maintenance before a persistent rise |
Test at least weekly and after changes in stocking, filter performance, feeding or behaviour. The numbers should be read together. For example, normal nitrate does not make detectable ammonia safe, and a stable pH does not compensate for inadequate oxygen. Our freshwater fish guide explains the wider planning context without replacing species-specific advice.
Do not sell or keep this fish as an algae-only cleaner. FishBase, drawing on the genus review by Freyhof and Serov, reports aquatic invertebrates in the stomach contents of wild S. marmorata. OATA's broader hillstream-loach guidance recommends prepared sinking foods and suitable live or frozen foods alongside mature grazing surfaces.
Offer a varied rotation of small sinking pellets or granules, quality wafers, and modest portions of suitable frozen or live foods such as daphnia, brine shrimp or small bloodworm. Choose pieces the fish can reach and rasp or pick from a surface. A food labelled for catfish or algae eaters is not automatically complete for this species; read the ingredients and include an appropriate animal-protein component.
Biofilm and soft natural growth are valuable for foraging and can supplement the diet, but the amount and nutritional content in a home aquarium are unpredictable. A bright patch of algae does not prove that the fish receives enough protein or total energy. Keep several mature stones available and continue deliberate feeding.
Place food in more than one location so one confident fish cannot guard the only feeding stone. Feed after checking that food reaches the bottom and is not taken first by faster mid-water fish. Observe individuals rather than assuming an empty wafer means everyone ate.
Body condition should remain even behind the head and across the abdomen. A fish that repeatedly loses position at food, becomes hollow-bellied or stops feeding needs prompt attention. Check competition, water quality, temperature and the food itself before adding more food indiscriminately.
Start with small portions that the group can finish, then adjust from direct observation. Remove persistent leftovers because decomposing food consumes oxygen and produces waste. Feeding more heavily to grow algae is not a safe strategy; light, surface maturity and controlled nutrients should be managed separately.
| Food type | Role | Caution |
|---|---|---|
| Small sinking pellet or granule | Measured staple with repeatable nutrition | Confirm it softens to a size the fish can take |
| Quality wafer | Surface-based feeding and group observation | Do not rely on an algae-only formula |
| Daphnia or brine shrimp | Small invertebrate component and variety | Use an appropriate particle size and avoid excess |
| Small bloodworm | Occasional animal-protein food | Not a complete daily diet |
| Mature biofilm | Foraging enrichment and supplementary natural food | Quantity and nutritional value are not guaranteed |
Expect the fish to spend much of its time close to glass, stone, wood and other solid surfaces. Movement can look like short glides between resting points rather than prolonged open-water swimming. A settled fish may forage in view, but it should also have shaded retreats and a choice of flow.
OATA recommends at least three or four hillstream loaches. Group living does not mean every individual shares one stone peacefully. Members of Sewellia can posture, displace one another and compete over preferred feeding surfaces. Provide more usable stones than fish, break lines of sight and spread food across the aquarium.
Brief displays without injury may be normal social negotiation. Persistent exclusion, damaged fins, weight loss or one fish being trapped away from food is not something to dismiss as harmless. Increase resources, reassess the layout and separate fish if welfare is compromised.
Yes, the commercial quantity selector works per fish, but husbandry still applies. Ordering one is suitable when it will join an established compatible group or when a specialist has a documented short-term management reason. It is not a recommendation for permanent solitary housing.
There is not enough product-specific evidence here to promise a fixed daily schedule. Activity changes with lighting, cover, food, tank mates and settlement. Provide a consistent day-night cycle and observe the individual rather than forcing a diurnal or nocturnal label into the sale.
Choose tank mates by environmental match first. A peaceful label is not enough if the other fish needs warmer, slower or chemically different water. Suitable candidates are small, non-predatory species that tolerate the chosen 18-24°C setting, strong oxygenation and active circulation without competing heavily for bottom food.
Small danios and White Cloud Mountain Minnows are often considered because many forms appreciate cooler, oxygenated water, but the exact species, group size and adult activity still need checking. Use the hillstream loach guide to compare the broader habitat before selecting a mixed community, then verify every species separately.
| Potential companion | Initial assessment | What must be checked |
|---|---|---|
| Compatible hillstream loaches | Preferred social context | Identity, group size, space, feeding surfaces and territorial behaviour |
| White Cloud Mountain Minnows | Often compatible | Chosen temperature, group size and enough open swimming room |
| Small cooler-water danios | Possible in a larger tank | Exact species, activity, feeding competition and current tolerance |
| Dwarf shrimp | Conditional | Adult shrimp may coexist, but shrimplets and small invertebrates are potential food |
| Snails | Conditional | Food competition, medication limits and whether the snail shares the water range |
| Goldfish | Usually avoid as a default pairing | Waste load, adult size, feeding pressure, flow and the exact goldfish setup |
| Bettas, Discus and warm-water dwarf cichlids | Poor default match | They commonly need warmer or calmer conditions and may create territorial conflict |
| Large or predatory fish | Avoid | A small loach can be injured, swallowed or excluded from food |
Browse the Loaches and Oddballs collection for current alternatives, but do not assume that every fish in one shop category shares the same temperature, current or social needs. Category membership is navigation, not compatibility evidence.
Prepare the aquarium before dispatch. The filter must be mature, ammonia and nitrite must read zero, the temperature must be stable, intakes must be guarded and the lid must be secure. Do not order the fish while a new aquarium is still cycling or while a major layout change is clouding the water.
On arrival, dim the aquarium lights and inspect the sealed bag before opening it. Follow the current instructions supplied with the order because journey time, bag water and temperature affect the safest method. Avoid leaving shipped fish in opened transport water for an unnecessarily long generic drip routine, especially when waste has accumulated during travel.
Use the water matcher to compare readings and the acclimation timer to manage the selected method. Transfer the fish with as little transport water as practical and do not add medication or salt automatically. Observe breathing, grip, posture and feeding closely during the first week.
Provide a shaded smooth surface near moderate circulation, keep disturbance low and offer only a small amount of food after the fish has settled. A new arrival may take time to choose a preferred surface. Persistent gasping, loss of balance or inability to hold position requires an immediate check of temperature, oxygen and water quality.
Good health begins with habitat, not a medicine cabinet. Check the fish daily for even body condition, clear fins, normal breathing, controlled movement and interest in food. Also check the system: thermometer, flow, filter output, intake guards and surface agitation.
These signs do not identify one disease. Test temperature, ammonia, nitrite, nitrate, pH and equipment first, then seek advice from a competent aquatic professional or vet where needed. Do not copy a medication dose from a forum without confirming the diagnosis, product instructions, water volume and species sensitivity.
Record water tests so a gradual change is visible before it becomes a crisis. Siphon trapped debris without stripping all mature surfaces, condition replacement tap water, and avoid cleaning every filter medium and stone on the same day. Rinse reusable filter media gently in removed aquarium water when maintenance is required, following the filter manufacturer's instructions.
Keep a contingency aerator or other oxygenation option available. A circulation or filter failure matters quickly in a warm, heavily stocked aquarium. Test backup equipment rather than discovering during an outage that tubing, batteries or air stones are missing.
This listing is unsexed. The supplier provides no male or female option, and body pattern alone is not a dependable sexing method. Do not order a fixed number expecting a guaranteed pair. Specialist examination of mature fin structures and breeding condition may help, but that is outside the promise of this retail listing.
There are hobby reports of Sewellia breeding in mature aquariums, including reports attributed to S. marmorata, but the sources available for this product do not justify a step-by-step species-specific breeding recipe.
If breeding is the aim, start with confirmed identity, excellent long-term husbandry, a compatible group, mature surfaces and a plan to document rather than assume what occurs. Protect possible juveniles from filters and tank mates only after obtaining specialist guidance. Never advertise offspring as pure S. marmorata when the adults were not reliably identified.
No exact lifespan promise is made. Generic aquarium pages quote figures for other hillstream loaches, but age at purchase, source, genetics and husbandry are unknown here. The responsible commitment is to provide suitable lifetime care rather than treating an unsupported range as a guarantee.
Sewellia marmorata can be confused in trade with Sewellia lineolata, undescribed Sewellia forms, Beaufortia, Gastromyzon and other flattened loaches. A shared body plan does not make the names interchangeable. Pattern can help orient an expert, but mouth structures, fin characters, locality and specimen-level examination may be needed for a confident identification.
| Fish or group | Useful distinction | Buying implication |
|---|---|---|
| Sewellia marmorata | Supplier identity for this SKU; central-Vietnam species with published 5.9 cm SL maximum | Use this page's species caveats and do not substitute another trade name silently |
| Sewellia lineolata | A different accepted species, widely called Reticulated or Tiger Hillstream Loach | Do not use its breeding or appearance claims as automatic evidence for this fish |
| Beaufortia species | Another hillstream-loach genus with a similar flattened silhouette | Confirm the scientific name because temperature, adult size and trade origin can differ |
| Otocinclus | Small South American suckermouth catfish, not a hillstream loach | Similar grazing language does not make the aquarium requirements interchangeable |
| Bristlenose Pleco | South American loricariid catfish with a different body, size and waste load | Choose by adult needs, not by the shared ability to attach to surfaces |
When browsing a general tropical fish range, keep the temperature distinction in mind. Retail navigation may place this fish beside warmer species, but a product category does not change its preference for a cooler, oxygen-rich setup.
Check the live product controls for current price and availability; those values come from Shopify and are intentionally not hard-coded into this description. If the product is out of stock, use the page's availability tools or browse alternatives rather than relying on an old price sentence captured by a search engine.
Confirm that the aquarium is at least 80 litres for a small group, fully cycled, covered and able to maintain 18-24°C with dependable oxygenation. Check the existing group, adult tank mates, summer room temperature and the number of safe feeding surfaces. A powerhead purchased on the same day does not turn a new tank into mature habitat.
Eligible first-time customers can use WELCOME10 for 10% off their first order. Livestock orders are covered by the Live Arrival Guarantee when the current delivery, receiving, evidence and contact conditions are followed. Read the returns and Live Arrival Guarantee terms before dispatch so someone is ready to receive and inspect the parcel promptly.
The guarantee covers eligible arrival outcomes under its published conditions; it does not replace preparing suitable water or monitoring the fish after introduction. Contact the team within the stated time if there is a problem and keep the required evidence. Do not delay while changing the aquarium in response to social-media advice.
FishBase records a maximum of about 5.9 cm standard length. Standard length excludes the tail fin. The approximate 3-4 cm on this product is a dispatch band, not an adult-size claim or exact measurement guarantee.
Use at least 80 litres for a small group of three or four, following OATA's hillstream-loach guidance. A long footprint is more useful than a tall narrow shape because it provides more stones, feeding sites and flow choices.
OATA advises keeping at least three or four hillstream loaches. One fish from this listing should normally join an established compatible group rather than remain permanently solitary. Provide enough space and surfaces for individual choice.
Use 18-24°C as the practical OATA range for hillstream loaches. Keep the chosen temperature stable and shared by every tank mate. At the warm end, pay particular attention to oxygen and summer heat.
OATA gives pH 6.5-8.0, 4-12 dGH and 3-10 dKH for hillstream loaches. Test the source and aquarium water and avoid rapid chemical adjustments merely to reach a central number.
It needs clean, highly oxygenated water and purposeful circulation. Species records also mention relatively slow current around some shallow rapids and deeper pools. Create stronger flow paths plus calmer resting pockets instead of blasting the entire aquarium uniformly.
No. It may forage on natural surface growth, but it is not a maintenance tool. FishBase records aquatic invertebrates in wild stomach contents, and the fish needs deliberate varied feeding. Control algae through light, nutrients and aquarium maintenance.
Offer small sinking pellets or granules, quality wafers and modest suitable frozen or live invertebrate foods such as daphnia or brine shrimp. Mature biofilm is useful enrichment but should not be the only food source.
It is conditional. Adult shrimp or compatible snails may coexist, but small invertebrates and shrimplets can be eaten and food competition is possible. Do not make the pairing when every baby shrimp must survive.
Goldfish are not a reliable default match because adult size, waste load, feeding competition and preferred flow differ. A specialist might assess a particular system, but a purpose-planned hillstream community is the safer recommendation.
No. S. marmorata and S. lineolata are different accepted species. Similar trade photographs and shared common names cause confusion, so this listing keeps the supplier scientific identity visible and avoids borrowing species-specific claims.
No. This product is sold unsexed and the supplier provides no sex option. Pattern and body fullness are not reliable enough for a retail guarantee, and a fixed quantity does not promise a pair.
The evidence reviewed for this product does not support a confident species-specific recipe. Hobby reports exist, but egg placement, sexing and fry care should not be presented as guaranteed facts. Obtain specialist guidance and confirm adult identity first.
No. The established gallery scenes are representative and illustrative. They do not guarantee the exact individual, markings, sex, age, origin or size. Supplier identity and the approximate dispatch band are stated separately.
New customers who qualify can enter WELCOME10 at checkout for 10% off a first order. Livestock purchases may also receive our Live Arrival Guarantee, provided the delivery, receiving, photographic-evidence and contact requirements in the current terms are met.
This page separates supplier facts, current commerce data and external care evidence. Petra Aqua supplies the sale identity and approximate dispatch size. Shopify supplies live price, inventory, status and availability. The following references support taxonomy, habitat, welfare and general home-aquarium planning:
Where reliable species-specific evidence was absent, the page says so. It does not promise lifespan, sex, exact breeding behaviour, captive-bred origin, a collection locality or an exact pictured fish. For broader shopping and preparation, visit the buying guide; for current delivery conditions, always use the dedicated policy pages linked above.
