rm
Passport
- Family
- Tetras
- Grows to
- 4.5 cm (1.8")
- Lives
- 4–5 years
- Temperament
- Peaceful
- Care
- Beginner
- Swims
- Mid-water
- Keep
- In a group of 6 or more
- Water
- 22–28 °C (72–82 °F)
GuyanaSurinameBrazil
Care requirements
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On record for X-Ray Tetra: adult size, lifespan, minimum tank, temperature, ph, hardness, minimum group, diet, care level, swim level, tank length.
A figure that is not on record is left out rather than guessed. One marked Suggested comes from keeping knowledge rather than a page.
- Minimum tank 57 L / 15.0 US gal
- pH 6–7.5
- Hardness 2–20 dGH
- Diet micropredator
- Tank length 60 cm minimum
Care notes written from general aquarium knowledge, not from the cited sources.
About
X-rays are the tetra you can see through. The body is genuinely transparent, and what shows through it is the chain of small bones running from the swim bladder to the inner ear — the mechanism that lets a fish hear. Very few animals put their own anatomy on display like this.
The fins are the other half of the fish: black, white and yellow bands on the dorsal and anal, which flicker as the shoal turns and are the only part of an x-ray that reads at a distance.
They're unusually adaptable, and there's a reason for it. They live on savannah floodplains that flood and dry every year, so the water they evolved in swings from soft and acidic to hard and mineral-rich over a season. Hardness barely matters to this fish, which is not something you can say about most tetras.
Tank setup
Plant your x-rays well and they'll show. In a sparse tank a transparent fish is close to invisible, and people who buy them for a bare setup wonder where they went.
Use a dark substrate and dim light. Wood, twisted roots and a layer of dried leaves suit them, and the tannins turn the water the colour of weak tea, which is exactly the background that makes a see-through fish visible.
Aquatic plants aren't really a feature of their natural water, so a leaf-litter and wood arrangement is the honest version. Java fern, anubias and crypts will fill it out if you want plants anyway.
Water chemistry is close to a non-issue here. Keep it stable and they'll be fine anywhere in the ordinary range.
Feeding
X-rays are micropredators that live on small invertebrates in the wild, and in a tank they're not remotely fussy. Flake and granules go down without hesitation.
Feed live and frozen food regularly regardless. Daphnia, brine shrimp and small bloodworm keep the fins bright and the fish in condition, and a micropredator on dried food alone slowly loses both.
Their mouths are small. Grade the food down further than you think you need to.
Avoid: large pellets and anything that sinks straight past them into the substrate.
Filtration and flow
Gentle to moderate flow suits them. They're floodplain fish used to slow, shallow water rather than current.
Standard filtration is fine and they tolerate a wide range of conditions, which makes them a genuinely good beginner tetra. An air-driven sponge filter matches the setup they look best in.
Change water regularly. Adaptable is not the same as indifferent, and a neglected tank still shows on them eventually.
With plants
X-ray tetras are entirely safe with plants and won't touch them.
Plant for contrast rather than for the fish's sake. Dark, dense growth at the back gives you something to see them against, which matters more here than in any other tetra because of what they are.
Fine-leaved plants and moss are worth adding if you'd like eggs to survive on their own.
Health
They're hardy and undemanding, and there's no ailment particularly attached to them.
The transparency is a diagnostic gift. You can often see problems inside an x-ray tetra that would be hidden in any other fish — internal parasites, a swollen gut, food that hasn't moved through. Use it.
Ich shows up starkly against a clear body too, which means you'll catch it earlier here than elsewhere in the tank.
Breeding
X-rays spawn easily and rearing the fry is the hard part. They scatter eggs among fine-leaved plants and eat them afterwards, like most tetras.
In the wild they breed in the wet season, when the floodwater is at its softest and most acidic, and that's the condition to reproduce. Soft, acidic water in a dim separate tank with moss or a mesh floor will get them going even though hardness is irrelevant the rest of the year.
The fry are very small. They need infusoria or a micron-graded food before they can take baby brine shrimp, and that first week is where most attempts fail. Keep the tank shaded while the eggs and young fry are light sensitive.
Tank mates
Avoid9
- Convict Cichlid Convict Cichlid grows to 15 cm against X-Ray Tetra at 4 cm, big enough to eat it.
- Jewel Cichlid Jewel Cichlid grows to 15 cm against X-Ray Tetra at 4 cm, big enough to eat it.
- Pictus Catfish Pictus Catfish grows to 12 cm against X-Ray Tetra at 4 cm, big enough to eat it.
- Common Goldfish Common Goldfish is not safe with X-Ray Tetra: common goldfish and tetras are a bad pairing.
- Demasoni Cichlid Demasoni Cichlid is not safe with X-Ray Tetra: african cichlids and tetras are a bad pairing.
Only with care10
- Chinese Algae Eater Chinese Algae Eater is aggressive and X-Ray Tetra is peaceful.
- Cherry Barb X-Ray Tetra and Cherry Barb are an uneasy mix: barbs and tetras are a pairing to watch.
- Gold Barb X-Ray Tetra and Gold Barb are an uneasy mix: barbs and tetras are a pairing to watch.
- Odessa Barb X-Ray Tetra and Odessa Barb are an uneasy mix: barbs and tetras are a pairing to watch.
- Paradise Fish Paradise Fish is a risk to X-Ray Tetra: large gouramis and tetras are a pairing to watch.
No conflict is recorded with the other 85 species in the database, so nothing to flag. 4 species are not covered at all, so they could not be judged either way.