X-ray Tetra Care Guide - Tank Setup, Feeding & Breeding

The X-ray Tetra is a small, lively characin named for its unusually translucent body. Through its silvery, glass-like flanks, the fish’s backbone and internal structure can often be seen, while a yellow-and-black dorsal pattern and red, yellow and black markings on the tail add colour. Its transparent appearance is especially striking when the fish moves through a well-lit aquarium as a coordinated group.

These peaceful fish are active midwater swimmers and are at their best when kept in a shoal. They spend much of their time weaving through open water, occasionally investigating plants and other cover, and their constant movement brings energy to a community aquarium without making them aggressive.

In nature, X-ray Tetras inhabit slow-moving streams, flooded areas and calm margins of larger waterways. Their habitats may contain dense vegetation, leaf litter and submerged branches, creating a mixture of open swimming space and shaded retreats. Seasonal changes can expose them to a broad range of water conditions.

Pristella maxillaris has long been popular in the aquarium hobby because it combines attractive markings, a manageable adult size and generally adaptable behaviour. Although hardy compared with many delicate tetras, it still shows its best colour and most natural behaviour when kept socially in a mature, well-maintained aquarium.

X-ray Tetras originate in northern and eastern South America, including the Amazon and Orinoco drainage regions of Brazil, Venezuela and the Guianas. They also occur in coastal waterways and are notably tolerant of mildly brackish conditions in some parts of their natural range.

A group of X-ray Tetras should have at least 60 litres, with a footprint of around 60 by 30 cm or larger. Provide open swimming space through the middle of the aquarium, along with planted areas, floating plants, driftwood and subdued zones that allow the fish to feel secure. A dark, fine-grained substrate can enhance their translucent bodies and markings, while gentle filtration and some water movement are suitable. They appreciate stable, clean freshwater and a tightly covered aquarium because they may jump when startled.

Up to about 4.5 cm (1.8 in) in total length. Females are usually slightly larger and deeper-bodied than males.

X-ray Tetras are omnivores and should receive a varied diet of quality small flakes or micro-pellets supplemented with frozen or live foods such as daphnia, baby brine shrimp, mosquito larvae and cyclops. Feed small portions that they can consume quickly, with variety helping to support colour, condition and breeding readiness.

X-ray Tetras are peaceful community fish that suit similarly calm species such as harlequin rasboras, small danios, other peaceful tetras, Corydoras, kuhli loaches, honey gouramis and small livebearers. They should not be housed with large predatory fish, fin-nipping species or boisterous tankmates that may intimidate them. Their small size also makes them unsuitable companions for fish large enough to swallow them.

X-ray Tetras are egg-scattering spawners that can be bred in a separate, dimly lit aquarium with very clean, soft to moderately hard water and fine-leaved plants or spawning mops. Condition a group with live or frozen foods, then introduce the adults when females are full of eggs. Spawning usually occurs among the plants, after which the adults should be removed because they may eat the eggs. The eggs hatch in roughly 24 hours, and the free-swimming fry can initially be fed infusoria or another suitably tiny first food before moving on to baby brine shrimp.

Females are generally larger, broader and more rounded through the belly, particularly when carrying eggs. Males are usually slimmer and may appear slightly more delicate, although the difference is modest in young fish.