Should I buy it?
Hillstream Loach
Sewellia lineolata
Also known as: reticulated hillstream loach, butterfly hillstream loach
A river-adapted loach that requires fast, highly oxygenated flow unlike any other aquarium fish. Still or gentle water is lethal over time.
Hillstream Loach tank mates · 100L tank size hub
peaceful · advanced care
Sources & confidencehigh · partially verified · beginner: not recommended
Checked against several solid care sources that mostly agree. Numbers here are a careful starting point. Your tap water, tank size, and habits decide the rest. How we evaluate.
Best for: High-flow specialised hillstream tanks with powerheads creating turbulent current and abundant algae biofilm on rocks.
Avoid if: Standard planted community setups with gentle circulation. Hillstream loaches slowly starve without the right conditions.
Common mistakeUsing standard aquarium filtration for hillstream loaches is how keepers invent lethargic, thin fish glued to glass without grazing. They need high turnover and powerhead-driven flow over rock. Build a river-style system first — a calm community filter is the wrong tool for Sewellia lineolata.
Top things that go wrong
- Specialist husbandry. Keep at least 3, bought at the same time.
- Shrimp & snails. Cherry shrimp and other dwarfs can coexist with peaceful small fish; baby shrimp are food for almost anything that finds them.
What most shops don't tell you
- 1.Myth: hillstream loaches are easy algae cleaners for any still planted community tank with normal filtration. Reality: they need strong flow, high oxygenation, and biofilm on rock — standard calm filtration leaves them stressed, thin, and underfed for months on end.
- 2.Tropical 26°C tanks with low flow. Hillstreams want 18 to 23 °C and strong directional current.
- 3.Treating them as algae eaters in a community tank. Without biofilm and turbulent water, they starve in clean setups.
- 4.Powerheads, sponge filters, and surface agitation matter as much as volume. An unpowered nano bowl is not a substitute for a proper riffle tank.
- 5.Advanced species — research stable parameters before buying.
About this species
Rheophilic loach from cool fast oxygen-rich Asian riffles. Standard tropical community temperatures with weak flow are a common failure mode.
- Zebra Loach120L min · same group, comparable tank size
- Kuhli Loach70L min · same group, similar adult size
- Dojo / weather loach150L min · same fish family
- Yoyo Loach200L min · same fish family
- Clown Loach400L min · same fish family
- Chocolate gouramialso advanced peaceful, similar tank size
- Splash tetraalso advanced peaceful, similar tank size
No reverse lookups listed yet.
Plan grid
Key limits are above. Here: pH band, swim level, bioload, and activity.
Swim zones
Care snapshot
Quick compare before you buy. Not a score of how “good” the fish is.
- Beginner ease26
- Peacefulness82
- Community fit66
- Small-tank fit100
- Hardiness24
- Energy54
Numbers are deterministic planning indices from Fishori fields — not a scientific score of your individual fish.
Example setups
Starting points only. Run the pair checker for every fish you add.
Rough 100L+ layout: one calm centrepiece, 8–12 small tetras/rasboras, 6–8 corydoras-type bottom fish — verify every name in the pair checker before buying.
Safer directions include: Pearl Danio, Zebra Danio.
Avoid “one of everything” baskets — Hillstream Loach belongs in a plan built around territory, line-of-sight breaks, and matched water chemistry.
Compatibility
Tank mates for Hillstream Loach
Usually safer (engine GOOD): Pearl Danio, Zebra Danio. Conditional (CAUTION — read the pair page before buying): Betta, Otocinclus, White Cloud Mountain Minnow. Avoid (RISKY): Discus, Jack Dempsey, Oscar. Every name links to a live pair check — the lists are a shortlist, not a stocking plan.
Usually safer
Open a pair page with this fish as the starting point.
Needs planning
Read the blocking rule on each pair page before experimenting.
Usually avoid
Do-not-stock combinations on conservative hobby rules.
Compare with
Run a real pair check: Hillstream Loach + Pearl Danio
- Try Pearl Danio — open the pair check.
- Try Zebra Danio — open the pair check.
Behaviour and temperament
Hillstream loaches are peaceful toward fish when flow and space are honest in a river-style layout. They may jostle for prime rock faces inside the group. Stress shows as clamped posture and weight loss when current and oxygen never match a real stream.
What sets them off
- Sudden crowding
- Poor water quality
Fin nipping: Not a habitual fin-nipper; stressed or crowded individuals can still test fins.
Predation: Not a predator toward similarly sized community fish; fry and dwarf shrimp are still fair game for most species.
Territory: Holds a patch (cave, corner, or surface). Break sight lines so neighbours can pass.
Planted tanks: excellent — easy plant ideas
In the glass: typical and warning signs
- Three or more graze rock faces in fast, well-oxygenated water.
- Holding station against current is normal ownership, not distress alone.
- Lethargy in a still planted cube means flow failed before diet tweaks.
- Thin bodies with closed mouths usually mean biofilm and current both failed.
- Low malice toward fish; mild jostling for grazing spots is normal.
- Boisterous midwater fish can outcompete them at every feed in tight tanks.
- Add powerhead flow before rehoming a 'lazy' hillstream.
- Feed into current after lights soften so wafers reach the rock face.
Fish behaviour can vary between individuals and tank setups. Always observe new fish closely after introduction.
Water, food, and grouping
Hardness
medium
Diet
omnivore
Hillstream loaches are omnivore grazers that need biofilm, algae wafers, and fine foods delivered in strong current — not a still planted nano schedule. Feed where flow carries particles across the rock face, keep a group of three or more on mature surfaces, and never expect them to thrive on leftover flake in dead water.
Shrimp & snails
Cherry shrimp and other dwarfs can coexist with peaceful small fish; baby shrimp are food for almost anything that finds them.
Keep at least 3, bought at the same time.
- Hold 20 to 25 °C steadily on a real thermometer, not the dial on the heater.
- Aim for pH 6.5 to 7.5 and a hardness you can re-test in two weeks. A one-time strip in the shop car park is not a water test.
- Footprint: short wide tanks and tall narrow tanks fish differently for the same volume. Match the tank shape to the swim pattern, not just the litre count.
- Tank volume meets or exceeds 100L published minimum for adults.
- You can stock at least 3 individuals (group welfare).
- Heater can hold 20–25°C without cooking cooler-water tank mates.
- Filter maturity / stable parameters before adding sensitive stock.
Explore and stocking hubs
Tank-mates hub, matching guides, category peers, and litre stocking lists around this species’ minimum tank.
Plan with tools
Check mates as pairs first, then add this fish in the tank builder for the full stocking.
Filtration & heating
A 100L minimum tank needs a filter rated for at least 400L/hr turnover and a heater to hold 20–25°C reliably.
Plant suggestions
Hillstream Loach does well in planted tanks. Plants compatible with 20–25°C and pH 6.5–7.5:
Research: partially verified · Confidence: high · 3 linked source(s). We do not invent citations.
How Fishori evaluates compatibility (same logic as pair and tank tools).
- Seriously Fish. Sewellia lineolata
Primary: aquarium size, water chemistry, behaviour, and compatibility (URL verified in upgrade script; recheck if site content changes).
- FishBase. Sewellia lineolata
Secondary: taxonomy, distribution, and maximum length in nature; cross-check with aquarium import lines and measured tank parameters.
- Wikipedia. Sewellia lineolata
Secondary: general species context; verify all husbandry numbers against a dedicated aquarium care sheet and your test kit, not a single table row.
Evidence notes
- The Seriously Fish profile for the binomial in this record was successfully reached as the primary aquarium reference.
- FishBase contributes natural-range size and habitat context. Translate those numbers through your heater, your water report, and your tank footprint before stocking.
- Wikipedia is only cited if the article URL returned OK. Use it for orientation, not as the only care sheet for an import.
- All compatibility text reflects typical hobby experience and the Fishori model. Individual fish, shop stress, and the order tank mates are added in can still defy a single-paragraph label.
Common questions about Hillstream Loach
- How big do Hillstream Loach get?
- Hillstream Loach adults reach about 7 cm. Shop fish look smaller; stock for the adult length.
- What size tank does Hillstream Loach need?
- 100L is the planning floor for adult swimming space and bioload. A 122L+ tank is the more comfortable long-term footprint. Length and depth matter as much as raw litres for active or territorial fish.
- Are Hillstream Loach aggressive?
- Hillstream loaches are peaceful toward fish when flow and space are honest in a river-style layout. They may jostle for prime rock faces inside the group. Stress shows as clamped posture and weight loss when current and oxygen never match a real stream.
- What is the most common mistake with Hillstream Loach?
- Using standard aquarium filtration for hillstream loaches is how keepers invent lethargic, thin fish glued to glass without grazing. They need high turnover and powerhead-driven flow over rock. Build a river-style system first — a calm community filter is the wrong tool for Sewellia lineolata.
- What fish can live with Hillstream Loach?
- The Hillstream Loach profile lists Pearl Danio, Zebra Danio among its safer pairings (engine-checked GOOD). Betta, Otocinclus, White Cloud Mountain Minnow are conditional (CAUTION): workable only with the specific conditions on each pair page. Avoid Discus, Jack Dempsey, Oscar (RISKY). Run the pair checker for your exact water and tank size before stocking.