Should I buy it?
X-ray tetra
Pristella maxillaris
Also known as: x ray tetra, water goldfinch, Water goldfinch
Fishori provides conservative planning guidance, not guarantees.
Based on multiple reputable aquarium care sources with strong agreement. Use the numbers here as planning defaults — your room, water, and routine still shape real-world outcomes.
A transparent-bodied schooler with a visible spine. Easy to keep, tolerates moderate hardness, and schools tightly in groups of eight.
Best for
Community tanks 60L or more with neutral to moderately hard water and a school of eight.
Avoid if
You keep anything that eats 4.5 cm fish, or your water is very soft and acidic.
Top things that go wrong
- Group welfare — not a solo display fish. Plan at least **6** together for normal behaviour; smaller groups often mean stress, colour loss, or nipping depending on species.
- Shrimp & snails. Shrimp: compatible in most setups. Cherry shrimp and other dwarf species coexist with peaceful small fish, though baby shrimp are food for almost any fish that gets to them.
Common mistakeFour x-ray tetras. They school so tightly in large groups that the transparent bodies create a visible pattern in motion; four fish don't produce this.
What most shops don't tell you
- 1.Stocked from soft-water-only literature without drip acclimation when the tap is moderate hardness.
- 2.Housed with fin-nippers in bare tanks with nowhere to break line of sight.
- 3.Six or more for the school. Pair with calm mid and bottom fish. They want a stable mature filter and regular water changes; the colour fades in spikes.
About this species
X-ray tetras are translucent characins with a yellow-and-black banded tail. Hardier than most rainforest tetras: they tolerate harder water and a wider pH range, though planted setups still bring out the best colour.
- Beckford Pencilfish60L min · same group, comparable tank size
- Black Neon Tetra60L min · same group, comparable tank size
- Bloodfin tetra60L min · same group, comparable tank size
- Cardinal Tetra60L min · same group, comparable tank size
- Glowlight Tetra60L min · same group, comparable tank size
- Green neon tetra60L min · same group, comparable tank size
- Lemon Tetra60L min · same group, comparable tank size
- Silver Tip Tetra60L min · same group, comparable tank size
- Amano Shrimpalso beginner peaceful, similar tank size
- Assassin Snailalso beginner peaceful, similar tank size
- Beckford Pencilfishalso beginner peaceful, similar tank size
- Black Neon Tetraalso beginner peaceful, similar tank size
- Black phantom tetraalso beginner peaceful, similar tank size
- Bloodfin tetraalso beginner peaceful, similar tank size
No reverse lookups on file yet.
Plan grid
Key limits are shown above; this section adds planning detail: pH band, swim level, bioload and activity, and the radar.
Swim zones
Planning trait chart
Six indices for comparing species on paper before you spend.
- Beginner ease82
- Peacefulness90
- Community fit83
- Small-tank fit100
- Hardiness76
- Energy54
Numbers are deterministic planning indices from Fishori fields — not a scientific score of your individual fish.
Common setup sketches
Conservative patterns from Fishori fields — still run the pair checker for every species you add; sketches are not a stocking guarantee.
Rough 90L+ layout: one calm centrepiece, 8–12 small tetras/rasboras, 6–8 corydoras-type bottom fish — verify every name in the pair checker before buying.
Safe directions on file include: Ember Tetra, Pygmy Corydoras, Chili Rasbora.
Prioritise 6+ of X-ray tetra in 60L+ with filtration sized for messy feeding — add only mates that already pass pair checks with this species.
Tank mate intelligence
Use the "Often compatible" lists as a shortlist, not a stocking plan. Always run the pair tool and check the footprint of your actual tank first. Verify behaviour for X-ray tetra against your own reading before you buy.
Pair-level compatibility with this fish as anchor.
Read the blocking rule on each pair page before experimenting.
Do-not-stock combinations on conservative hobby rules.
Compare with
Run a real pair check: X-ray tetra + Ember Tetra
Behaviour, temperament, and what to watch
Prose and lists come from the same record: read temperament first, then glass-level signals so you are not surprised after day three.
X-ray tetra is peaceful in mixed company.
Stress / aggression triggers on file
- Sudden crowding
- Poor water quality
Fin nipping: Not a habitual fin-nipper, but individuals can still test fins under stress or in a crowded tank.
Predation: Not a predator toward similarly-sized community fish. The usual community caveats about mouth size still apply for very small fry or shrimp.
Territory: Not strongly territorial, but still claims a working area in the tank. Give it room to settle without overlapping the next species' patch.
Planted tanks: excellent — easy plant ideas
In the glass: typical and warning signs
- Moderate pacing — not hyperactive, not motionless.
- Shoaling/schooling: most colour and confidence show when the group meets **6+**.
- Clamped fins, gasping at the surface, hiding non-stop, or refusing food after the first week.
- Rapid breathing when parameters swing — fix ammonia/nitrite first, then reassess mates.
- Low listed risk — still watch new introductions.
- Separate or rehome if injuries appear, one fish is pinned, or feeding becomes a daily chase.
- If water is stable but behaviour worsens, reduce stocking or remove the highest-impact species first.
Fish behaviour can vary between individuals and tank setups. Always observe new fish closely after introduction.
Care parameters: water, food, inverts, grouping
Chemistry and group rules sit here so you are not re-reading the same line from tank mate or temperament blocks. Swim level is in the plan grid above.
Hardness
soft
Diet
omnivore
Mixed diet: a quality flake or pellet as the staple, with frozen or live foods two or three times a week.
Shrimp & snails
Shrimp: compatible in most setups. Cherry shrimp and other dwarf species coexist with peaceful small fish, though baby shrimp are food for almost any fish that gets to them.
Shoaling species. Buy 6 or more of one species together. Smaller schools sulk, lose colour, and redirect their schooling energy at whatever else is in the tank.
Egg scatterers and schoolers still spawn in stable tanks. Have a plan for the fry, or accept that the parents and tank mates will eat them in a community setup.
- Hold 22 to 28 °C steadily on a real thermometer, not the dial on the heater.
- Aim for pH 5.5 to 7.5 and a hardness you can re-test in two weeks. A one-time strip in the shop car park is not a water test.
- Schooling species. Buy 6 or more from the same tank on the same day before adding any centrepiece fish.
- Tank volume meets or exceeds 60L published minimum for adults.
- You can stock at least 6 individuals (group welfare).
- Heater can hold 22–28°C without cooking cooler-water tank mates.
- No known fin-nippers paired with long-finned fish unless you accept documented risk.
Explore and stocking hubs
Same library as the rest of Fishori: tank-mate index for this species, category peers, guides, and litre-based stocking lists where min tank on file is within the hub volume.
Plan with tools
Pair-level rules and multi-fish stocking use the same conservative engine — add this fish in the tank builder only after mates pass pair checks.
Filtration & heating
A 60L minimum tank needs a filter rated for at least 240L/hr turnover and a heater to hold 22–28°C reliably.
Plant suggestions
X-ray tetra does well in planted tanks. Plants compatible with 22–28°C and pH 5.5–7.5:
Profile status: partially verified · Evidence tier: high · 3 linked source(s). Fishori does not fabricate citations.
Fishori uses conservative planning rules based on these sources.
Confidence is explained in the summary at the top of this page (same tier as here), not repeated below.
How Fishori evaluates compatibility (same logic as pair and tank tools).
- Seriously Fish. Pristella maxillaris
Primary: aquarium size, water chemistry, behaviour, and compatibility (URL verified in upgrade script; recheck if site content changes).
- FishBase. Pristella maxillaris
Secondary: taxonomy, distribution, and maximum length in nature; cross-check with aquarium import lines and measured tank parameters.
- Wikipedia. Pristella maxillaris
Secondary: general species context; verify all husbandry numbers against a dedicated aquarium care sheet and your test kit, not a single table row.
Evidence notes
- The Seriously Fish profile for the binomial in this record was successfully reached as the primary aquarium reference.
- FishBase contributes natural-range size and habitat context. Translate those numbers through your heater, your water report, and your tank footprint before stocking.
- Wikipedia is only cited if the article URL returned OK. Use it for orientation, not as the only care sheet for an import.
- All compatibility text reflects typical hobby experience and the Fishori model. Individual fish, shop stress, and the order tank mates are added in can still defy a single-paragraph label.
- Fishori profiles work from typical aquarium trade sizes and hobby care norms. Specialist site checks and literature review for this species are not yet recorded here, so the ranges on this page are planning numbers rather than guarantees.