细锯脂鲤 · X-ray Tetra

Overview

Pristella maxillaris, the X-ray tetra, is a peaceful, adaptable small schooling fish. Most specimens in the trade are commercially bred. Routine care is relatively straightforward; during breeding, the exceptionally small fry are more challenging than inducing the adults to spawn.

Distribution & habitat

Its native coastal range includes Venezuela, Guyana, Suriname, French Guiana, and northern Brazil. Clear streams and tributaries are occupied during the dry season. With the rains, fish enter flooded savanna and spawn among submerged vegetation. Seasonal flooding brings substantial changes in dissolved mineral content.

Aquarium setup

Provide a footprint of at least about 60 × 30 cm. Farmed fish adapt to various sensible layouts, but dense planting usually shows their colors better than a sparse aquarium. Sand, driftwood, roots, and leaf litter with subdued light offer another arrangement. Inspect and replace deteriorating leaves regularly.

The species tolerates a broad hardness range in routine care. Softer, more acidic conditions are more appropriate for breeding because they resemble the wet season. Commercial production locations should not be confused with the native range.

Diet & feeding

Wild fish mainly hunt small invertebrates. In captivity they are unfussy: combine flakes or fine granules with small live and frozen foods such as Daphnia and Artemia.

Behaviour & compatibility

Avoid much larger or very boisterous fishes that can outcompete this gentle species. Peaceful small schooling fishes, small catfishes, and suitable dwarf cichlids are possible companions. Keep at least six X-ray tetras, preferably ten or more, for better condition and more natural displays.

Sexual dimorphism

Mature females usually grow larger and are stockier than the slimmer males.

Breeding

Spawning itself is fairly easy, but supplying food small enough for the fry is crucial. Use a separate, very dim aquarium with fine plants, spawning mops, or protective mesh. Soft, acidic water and gentle sponge filtration are suitable; reverse-osmosis water can help prepare the conditions.

A group of around six fish per sex can spawn. Alternatively, condition males and females separately and transfer a gravid female with a well-conditioned male in the evening. Spawning usually follows the next morning. Pairs tend to be more productive; replace the pair if no eggs appear after a few days.

Remove adults after spawning because they eat eggs. An alternative in exceptionally dense planting is to leave them in place and siphon out fry promptly. Hatching takes roughly 24–36 hours, with free swimming three or four days later. Begin with infusoria-sized foods and progress to microworms and Artemia nauplii. Eggs and early fry are sensitive to light, so keep the rearing environment as dark as possible.

Notes

The selectively bred golden form is semi-albino and has essentially the same care requirements. Older literature often uses the former name Pristella riddlei.