Fish, Tanks and Ponds

Fish, Tanks and Ponds
A comprehensive guide to fish

Mesonoemacheilus triangularis

Zodiac Loach

Zodiac loach, Mesonoemacheilus triangularis Zodiac loach, Mesonoemacheilus triangularis
Photos by Andy Rapson


Nemacheilus: Greek, nema, -atos = filament + Greek, cheilos = lip

General Notes:

The aquarium should be set up to mimic their natural environment, a mixed substrate of coarse sand, pebbles of varying size and plenty of hiding places. The hiding places are very important in order to keep aggression down and to allow each individual its own territory. A good filter with a good flow rate should be used to keep the water clean and well oxygenated.

Other than that this is a relatively undemanding species.


Suitably sized live or frozen food - Blood worms, brine shrimps, daphnia, cyclops, mysis shrimps and similar.


Occasionally peaceful specimens are found but generally this species is quite feisty particularly among themselves. They can still be kept in groups provided that there are enough hiding places and that their aquarium is large enough to allow each fish to have its own territory. Other species are generally ignored unless they get to close.


There are no reliable differences between the sexes but as with other Cyprinids adult female may be larger than adult males and the females may be more rounded and heavier looking.


Although difficult this species has been bred in captivity. A pair were observed to use a spawning mop to lay their eggs the brood eventually resulted in approx 500 fry raised to a saleable size.

Wild status

Mesonoemacheilus triangularis is regularly caught for the fish trade but it remains common across its range and doesn't seem to be facing any immediate threats. But human activity is increasing across its range and although the population is thought to be stable at the time of writing (2015) this may change in the future.

Additional information

Nemacheilus triangularis was described by Day in 1865. The subspecies named as N. triangularis tambarapaniensis Menon, 1987 from Tambaraparani River could be a distinct species.

Information at a glance

pH: 7 - 7.5
dGH: Up to 12.
Temperature: 20 - 26°C (68 - 79°F)
Lighting: not critical.
Diet: Omnivore
Size: 5cm (2in)
Min tank size: 60 litres
Difficulty level: Easy
Aquarium type: Community
Swimming level: Bottom

Distribution and habitat

distribution map for Helostoma temminckii

Origin: Asia: Kerala and Kanyakumari District of Tamil Nadu in India

Habitat: Streams with stony bottoms.


Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Cypriniformes
Family: Nemacheilidae
Genus: Mesonoemacheilus
Species: M. triangularis, Day, 1865

Other common names:
Batik Loach

Noemacheilus triangularis tambaraparniensis,
Noemacheilus triangularis triangularis,
Mesonoemacheilus triangularis,