X-Ray Tetra

Pristella maxillaris

X-ray tetra, Pristella maxillaris, is a small characin from northern South America, including lower Amazon and Orinoco waters and coastal drainages of the Guianas. It is also sold as the Pristella tetra, x-ray fish, or water goldfinch. The body is partly translucent with a silvery-gold sheen, a red-orange tail, and crisp black, yellow, and white markings in the dorsal and anal fins. Wild fish use floodplain streams, swamps, and sometimes slightly brackish coastal habitats, which helps explain their adaptability in aquariums.

Aquarists keep x-ray tetras as peaceful schooling fish, usually in groups rather than singly. Captive-bred stock is common, including golden or albino forms, and they fit well in planted community tanks with other small, nonaggressive species. They accept fine flakes, micro pellets, and small frozen or live foods, but stable water and low stress matter more than chasing an exact pH number. Breeding is typical of egg-scattering tetras: adults do not guard the eggs and may eat them, so breeders use fine plants, spawning mops, or separate rearing tanks.