The pristella tetra fish, also called the X-ray tetra fish, goldfinch tetra, or signal tetra, is a small and hardy freshwater fish. It’s native to South America, where it migrates with the season, hence its high level of adaptability.
Like most tetra fish, they’re easy to keep, mild-tempered, and will get along well with other fish of a similar size and temperament. Their unique appearance is what has made them a favorite among aquarists.
Once you know their needs, distinguishing features, breeding, and tank mates, taking care of pristella tetra is easy.
Appearance and Size
The pristella tetra has a silver body transparent enough to see the internal organs. That’s what earned them the “X-ray” name. You can even see eggs develop in female bodies during breeding.
Female pristellas are stockier than males, although both sexes are wider in the middle of the body.
Their dorsal and anal fins have yellow, black, and white stripes. The vibrant yellow stripe is closest to the body and is followed by the staunch black stripe. Farthest from the body is the crisp white stripe.
Some pristella tetras have pink or red tail fins and yellow coloration at the caudal fork. Most have a black spot right behind their heads.
The average pristella tetra measures 1.75 inches, although they can grow to 2 inches long. This means they don’t need large tanks to thrive.
Lifespan
Pristella tetras live for 4 to 5 years under proper care. Their lifespan depends on the quality of care regarding their diet, tank mates, tank conditions, and stress levels.
Behavior
X-ray tetras are schooling fish that will form a shoal of 6 or more fish. Fewer fish will spend most of their time hiding. Schooling protects from predators. They’re also easy to spook and will run to hide when scared.
They’re calm fish that rarely fight. If they fight, it won’t amount to any serious harm. This behavior extends to other tank mates. They’ll be calm and stress-free if they’re not attacked. This calmness is exhibited in rainbow tetras.
Pristella Tetra Care
While a hardy species, the X-ray tetra still needs good care to thrive. Proper care for pristella tetra fish is as follows:
| Care Category | Level |
| Care level | Easy |
| Color | Translucent |
| Size | About 2 inches |
| Tank size | 10+ gallons |
| Tank mates | Small and peaceful |
| Temperament | Peaceful |
| Lifespan | 3 – 4 years |
| Tank setup | Plants, fresh water, enough space |
| Behavior | Schooling |
| Family | Characidae |
1. Tank Size
A school of pristella tetras (6 members) requires a tank of at least 10 gallons large. Ideally, give them a tank of between 15 and 20 gallons for better growth and development.
2. Water Conditions
In nature, X-ray tetras live in both soft and hard water. As such, they’re not affected by changes in the hardness and salinity of the water. Do not, however, expose them to brackish water at all times.
Keep them in the following parameters for the best results:
- pH: 5.8 – 8.5
- Temperature: 64 – 82°F
- Water hardness: 4 – 8 KH
These parameters make keeping them with other aquatic pets easy since they easily adapt to the prevailing conditions.
3. Food and Diet
These fish are omnivores and will eat most foods they’re offered. Feed them commercial pellets or flakes with an occasional high-protein treat for good health. Focus on a balanced diet to help them grow fast and healthy.
Besides pellets, feed them bloodworms and freshly-hatched brine shrimp (Artemia) to boost their health. The fish can also eat Daphnia, besides other live and frozen foods.
Feed them two to three times a day with just enough food to avoid leftovers that can soil the tank. Only provide the food they can eat within 3 minutes.
4. Tank Mates
X-ray tetras are peaceful fish and will coexist with aquatic pets of the same temperament. Ensure the other pets don’t harass the tetras as it causes stress to the latter.
Some of the best tank mates for pristella tetras include the following:
- Small tetra fish like flame tetras
- Pencil fish
- Guppy fish
- Molly fish
- Apistogramma (dwarf cichlid)
- Small Rasbora breeds
- Mild-tempered loaches
- Platy fish
- Danios
- Small barbs
- White Cloud Mountain minnows
- Corydoras
Large and aggressive tank mates will not only harass the X-ray tetras, but they’ll also eat them up. Some slightly larger tank mates can also coexist with most types of tetras like ember tetras with bettas.
5. Diseases
Luckily, there are no diseases specific to X-ray tetras. However, common fish diseases such as ich and fin rot can also affect these fish, especially in water with poor conditions.
Ich causes spots on the fish’s skin, while fin rot leads to their fins rotting and dying off. If you notice any of these diseases, isolate the affected fish, then treat it as directed by the vet.
With proper care, such diseases won’t affect the fish. You should focus on the water quality since that’s where most issues start.
Breeding
In my experience with fish, pristella tetras are among the easiest to breed since they do so quite easily. As long as you can recreate their natural breeding habitats, they’ll breed whenever they’re mature enough to do so.
In the wild, X-ray tetras migrate to areas with vegetation to breed among the plants. You recreate this habitat in their tanks by adding lots of plants (like java moss). Ideally, have a separate breeding tank for them. These same plants are used when hiding from predators, hence very important.
Breeding Tank Conditions
The breeding tank for your X-ray tetras needs to have the following conditions:
- At least 10 gallons large.
- Temperature: around 78°F.
- pH: near neutral (7).
- Cover filter inlets with sponges to stop eggs from going into the filters.
- Add plants with fine leaves for the fish to lay eggs on and the fingerlings to hide in.
Mating
Pristella tetras are quite picky when it comes to mating partners, and finding a match can be tricky.
Start by placing a pair of fish (male and female) into the breeding tank, then give them food high in proteins. If the female doesn’t swell with eggs in 2-3 days, try another male or female until it works.
Once the pair mates, the female will lay 300 to 400 eggs among the plants. After that, remove the fish immediately, as they’ll eat the eggs. You can have a mesh at the base of the tank such that eggs can fall through it but the adults can’t reach the eggs.
The fingerlings
X-ray tetra eggs hatch in 24 to 36 hours after they’re laid. The fingerlings feed on fine powdered foods and will grow to eat baby brine shrimp. They also feed on infusoria.
Adults can also eat the fingerlings, and the latter should be removed by siphoning them and then placing them in a tank where they can grow to reasonable sizes.
The fry will become free swimmers in 3 – 4 days and should be kept in low-light conditions since they’re highly light-sensitive.
Get some X-ray tetras!
Pristella tetras are a hardy breed that’s easy to keep. Whether you’re a seasoned aquarist or an upcoming one, you’ll find it easy to keep this small, hardy fish.
As observed in this guide, they don’t require much maintenance, feeding, or breeding. They also get along well with other aquatic pets and their schooling behavior is a joy. Start a small school of X-ray tetras today!
