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Species profile

Zodiac Loach

Mesonoemacheilus triangularis

Common names: Zodiac Loach

Recognized speciesLoaches
Zodiac Loach (Mesonoemacheilus triangularis)

Adult size

Up to 8 cm

Typical adult length 5.6–8 cm.

Up to 8 cm

Countries of origin

  • See all stock from India

Good fit for your tank?

Good fit for

  • Keepers able to provide at least a 75 cm aquarium with the substrate, current, and cover this loach needs.
  • A mature aquarium where bottom-feeding fish receive targeted food and regular maintenance.

Think carefully if

  • The aquarium is shorter than 75 cm or cannot support the recommended social group.
  • The aquarium has coarse substrate, unprotected filter gaps, or aggressive competition at the bottom.

Zodiac Loach is a bottom-dwelling loach requiring a 75 cm or longer aquarium, suitable substrate, stable water, and species-appropriate social housing.

Appearance and Identification

A slender Indian stream loach with triangular dark flank markings, mottled fins, and a pale brown ground colour.

Prefers cool, clean, well-oxygenated water and a structured rocky floor.

Sexes are difficult to distinguish reliably outside breeding condition. Mature females may become fuller through the abdomen, while males of some species develop stronger colour, fin shape, or breeding tubercles.

Tank Requirements

Suggested filter
About 320–400 litres an hour
Suggested heater
About 75–125 W for this tank
Minimum tank volume
80 litres
Minimum tank length
75 cm
Minimum group size
3
Recommended group size
5
Activity level
Moderate
Flow preference
High
Planting preference
Lightly planted
Hiding places
Yes
Lid recommended
Yes
Jumping risk
Medium

Set up a mature aquarium at least 75 cm long with clean, well-oxygenated water, smooth gravel and sand, rounded rock piles, crevices, and a secure lid. Arrange several separate shelters and keep detritus from collecting beneath hardscape.

Behaviour and Tankmates

Zodiac Loach is a bottom-dwelling stream loach that searches among stones and crevices for small prey. It may rest in cover, then move quickly into current or across the substrate when feeding.

Keep 3 to 5 where the species is peaceful and space permits. For more territorial forms, a single fish or carefully observed group in a larger footprint is safer.

Adults may defend caves, rock gaps, or feeding areas from similar-shaped fish. Provide broken sight lines and multiple retreats.

Choose peaceful or moderately active stream fish that share the same temperature and oxygen needs. Avoid tiny shrimp, slow bottom fish, and combining several territorial loaches in a small footprint.

Check tankmates for this species

Water Parameters

Temperature
20–26 °C
pH
6–7.5
GH
1–10
KH
0–6
TDS
30–180
Stability importance
Important

Maintain stable, clean water within the stated range. Oxygenation, low organic waste, and gradual acclimation are more important than forcing an exact pH or hardness value.

Parameter caveat
Match the supplier water during acclimation and change temperature or mineral content gradually. Rare wild-caught loaches may arrive adapted to narrower conditions than the general range suggests.

Feeding

Diet types
Carnivore, Insectivore, Omnivore
Feeding frequency
Daily
Preferred foods
  • Quality sinking carnivore or omnivore pelletsUse a small pellet suited to the fish’s mouth.
  • Frozen insect larvae and crustaceansOffer varied foods such as bloodworm, cyclops, Artemia, or Daphnia.
  • Live aquatic invertebratesUse occasionally for conditioning and natural hunting behaviour.

Offer small sinking foods rich in aquatic invertebrate protein. Combine a dependable prepared staple with frozen or live insect larvae, Artemia, Daphnia, or similar foods.

Feed small portions at more than one point because territorial fish may guard food in a confined area.

Breeding

Breeding type
Egg Layer, Egg Scatterer
Breeding difficulty
Difficult
Breeding temperature
23 °C
Breeding pH
6.8
Brood or egg count
Unknown or variable; species-specific aquarium counts are not dependable.
Incubation
3 days
Parental care
None
Baby foods
  • Infusoria or cultured microscopic foodUse when newly free-swimming fry are too small for Artemia.
  • MicrowormsIntroduce once fry actively search the bottom.
  • Newly hatched Artemia naupliiUse after fry are large enough to swallow nauplii.

Captive breeding is poorly documented. The fish is expected to scatter or deposit small eggs among gravel, stones, or vegetation without parental care. Seasonal cooling or warming, increased flow, and live-food conditioning may be important, but claims should be treated cautiously unless documented for this species.

Habitat and Origin

Geographic origin
Asia, India, South Asia
Natural habitat
Fast Stream, Freshwater Stream, Rocky Shoreline
Aquarium contexts
Freshwater Aquarium, High-Flow Aquarium, Species-Only Aquarium
Audience level
Specialist

Classification

Profile type
Recognized species
Genus
Mesonoemacheilus
Family
Nemacheilidae
Species group
Fish, Loaches

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