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Maximum size : 4 cm

Mountain Crystal Tetra - Protocheirodon pi : Complete Fish Profile & Care Guide

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Mountain Crystal Tetras (Protocheirodon pi) are a peaceful and active species that add a touch of uniqueness to any nano or planted aquarium. Though initially shy, these hardy and undemanding fish will settle in quickly under the right conditions. As schooling fish, it is essential to keep them in large groups of at least ten individuals, which will help them feel more secure and exhibit natural behaviour. 

When choosing tankmates, it is best to select species that are similar in size and temperament. Ideal companions include smaller Tetras, surface-dwelling species like Hatchetfish, and peaceful bottom dwellers such as Corydoras and Whiptail Catfish. However, it is crucial to avoid housing Mountain Crystal Tetras with aggressive or predatory tankmates, and having them as the only mid-water species is advisable.

These Tetras prefer a blackwater biotope setup with plenty of decor and plants to establish their territories and provide ample shade. Their transparent body displays tiny black dots covering the anal and dorsal fins, with a black mark on their caudal peduncle. Their swim bladder is also split in two, connected on top, forming a shape reminiscent of the ancient Greek letter Pi, which inspired their name.

Mountain Crystal Tetra Photos

Sexual Dimorphism

Determining the sex of Mountain Crystal Tetras can be pretty challenging as males and females are almost indistinguishable in appearance. However, mature females carrying eggs may appear fuller-bodied than males. Additionally, due to their transparent bodies, observing the eggs inside the female may be possible.

Quick Facts

Scientific NameProtocheirodon pi
Year Described1978
Other NamesPi Tetra
Max Size4 cm
Aquarium LevelMiddle
DifficultyBeginner - Intermediate
Best kept asGroups 10+
LifespanUp to 5 Years

Water Parameters

Water TypeFreshwater
PH6.0 - 7.5
GH5 - 20
76 - 82
24 - 27

Natural Habitat

Mountain Crystal Tetras are native to the beautiful and vast river systems of South America's central and western parts of the Amazon Basin, including the Madeira, Solimoes, Purus, and Ucayali rivers. These magnificent fish prefer to reside in the calm to moderately flowing, shallow backwaters of rivers and streams, usually over sandy substrates. You can often find them hanging out around submerged tree branches or the roots of aquatic plants, where they feel most at home.

 Ucayali River - Peru
Peru Flag


Regrettably, there is a dearth of available information regarding the breeding habits of Mountain Crystal Tetras. Nonetheless, one could hypothesize that their reproductive behaviour is akin to other members of the Characidae family.

Diet & feeding

Mountain Crystal Tetras are known to primarily feed on small insects and invertebrates that they obtain from the water's surface in their natural habitat. Therefore, it is essential to replicate this diet as much as possible in the home aquarium. To ensure optimal health and colouration of your fish, it is recommended that you provide them with a varied diet consisting of live, frozen, or freeze-dried foods such as brine shrimp, cyclops, daphnia, mosquito larvae, and bloodworm. High-quality dried food such as micropellets and flakes can also be offered and will be readily accepted by these Tetras. A well-balanced and diverse diet will ensure that your Mountain Crystal Tetras receive all the necessary nutrients for optimal growth and development.

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