fish · Mastacembelidae
Half-banded spiny eel
Macrognathus circumcinctus
Wild range: Mekong and Chao Phraya basins, southeastern Thailand, Malay Peninsula and Sumatra, Indonesia (FishBase); also recorded from Cambodia and more widely across mainland SE Asia. Type locality Talé Sap / Patelung River, Peninsular Thailand (Catalog of Fishes / Aquarist Atlas). (Asia)
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At a glance: Half-banded spiny eel care
Compiled reference information. Review the care notes and original sources below.
What temperature is listed for Half-banded spiny eel?
The compiled profile lists 24.0–28.0 °C for Half-banded spiny eel (Macrognathus circumcinctus). Check the original sources below for context and differing recommendations.
What tank size is listed for Half-banded spiny eel?
The profile lists a minimum tank volume of 55.0 US gallons (208.0 liters). Volume alone does not establish suitability; consider dimensions, group size and other inhabitants alongside the full care notes.
What pH is listed for Half-banded spiny eel?
The compiled profile lists a pH of 6.0–7.5. Review the cited care sources alongside the other water parameters in this profile.
Natural habitat
A small to medium Asian spiny eel (Mastacembelidae) with a long, scaleless-looking body, fleshy probing snout, and a series of regular oblique dark bars that typically stop partway down the flanks — the half-banded or belted pattern that separates it from peacock eels and many Mastacembelus. Nocturnal and burrowing: by day it often sits buried in fine sand with only the snout showing, then becomes active after lights-out to hunt invertebrates and occasionally small fish. Not a true eel (Synbranchiformes, not Anguilliformes).
Where they are found
Catalog primary Macrognathus circumcinctus (Hora, 1924) — valid in ITIS (TSN 650105), FishBase (SpecCode 55327) / Catalog of Fishes, and GBIF (accepted). Original combination Mastacembelus circumcinctus Hora, 1924; junior synonyms include Macrognathus taeniagaster (Fowler, 1935) / Mastacembelus taeniagaster Fowler, 1935 (CoF / Aquarist Atlas). Trade names: Half-banded spiny eel, Half-banded peacock eel, Belted spiny eel, Zigzag / Zig-zag eel, Half-barred spiny eel (Maidenhead; AquaInfo; AquariumAPI). Lookalike caution (species itself clear — no deferral): peacock-eel Macrognathus siamensis (also still missing from this catalog) has longitudinal eye-spots/striping rather than half-depth oblique bars; M. aculeatus and larger Mastacembelus (e.g. fire eel M. erythrotaenia, tyre-track) are sold as generic spiny eels and grow much larger. IUCN Least Concern (assessed 2019-12-11; FishBase 2025-2). FishBase max TL 28.6 cm is exceptional; hobby adults usually 12–20 cm.
Aquarium care
Plan at least a 55 US gallon (~208 L) tank with a long footprint for the recommended group of 5+: Studio Scaped gives ~30 gal / 120 L for a single adult, TankBud and App-aquatic give ~57 gal / 215 L, and Maidenhead stresses footprint over height for groups. Temperature 24–28°C (FishBase and Maidenhead 24–27; AquaInfo 24–28; Studio Scaped 23–28; Aquarist Atlas 24–29). pH 6.0–7.5 (Maidenhead 6.0–7.0 soft/acidic preferred; AquaInfo 7.0–7.5; TankBud 6.0–7.5; Aquarist Atlas 6.4–8.3). GH roughly 5–15 dGH (Maidenhead up to 15°; FishBase dH 15; AquariumAPI 5–15). Soft fine sand deep enough to burrow is mandatory — sharp gravel abrades the mucus coat and invites infection. Provide wood, caves, pipes, plants and leaf litter (catappa appreciated), subdued lighting, and a tight, gap-free lid (notorious escape artists). Moderate flow and mature, clean filtration; freshwater only (AquaInfo rejects the brackish myth). Intermediate difficulty: never add to an immature tank; copper-sensitive.
Feeding
Carnivore / micropredator: wild diet is benthic invertebrates, insect larvae, worms and small crustaceans, with occasional small fishes (FishBase; AquaInfo; Aquarist Atlas; Scientific Fishkeeper). Offer live or frozen bloodworm, mosquito larvae, brine shrimp, mysis, daphnia, blackworm and chopped earthworm/prawn; many refuse dry flake at first though some take sinking pellets or insect-based gels later (Maidenhead; Studio Scaped). Feed after lights-out — shy day feeders are easily outcompeted by midwater fish.
Compatibility
Peaceful toward similar-sized fish and suited to a softwater community of large rasboras, gouramis, peaceful botiids, Geophagus, L-number cats and medium tetras (Maidenhead; Studio Scaped). Will eat neon-tetra-sized and smaller fish overnight — choose tankmates carefully. Sociability with conspecifics varies: Maidenhead recommends groups of 5+; AquaInfo and Scientific Fishkeeper report both peaceful groups and intolerant singles — provide many hides and space, or keep one in a smaller tank. communitysafe true with those caveats; nanook false. Avoid aggressive bottom competitors and copper medications.
Breeding
Egg-scatterer; no reliable home-aquarium breeding record for this species (Maidenhead; Aquarist Atlas). AquaInfo notes a few breeding cases tied to heavy live food and water changes simulating the rainy season. Mature females may appear plumper; sexing otherwise difficult (Maidenhead; AquaInfo).
Sources
Compiled from multiple independent care sheets — not copied from a single site.