Ulrey’s Tetra Care Guide: Tank Setup, Diet, Tank Mates, and More

Table of Contents

• Key Takeaways
• Species Overview
• Classification
• Origin & Natural Habitat
• Appearance & Identification
• Average Size & Lifespan
• Care Guide
• Tank Mates
• Food & Diet
• Breeding & Reproduction
• Common Health Issues
• Common Mistakes to Avoid
• Where to Buy
• Frequently Asked Questions
• Closing Thoughts
• Recommended Video
• References

Ulrey’s tetra is one of those species that barely gets talked about in the hobby, and honestly, that’s a shame. This small characin from the Paraguay River basin has a clean, eye-catching look with its bold dark horizontal stripe and the golden band running just above it. It’s a subtle fish that stands out in all the right ways once you see a school of them moving together.

What I appreciate most about Ulrey’s tetra is how straightforward it is to keep. Hardy, peaceful, easy to feed, and comfortable in a wide range of water conditions. In my 25+ years in the hobby, I’ve always thought it deserved more attention than it gets. If you’re after a tetra that’s a little different from the usual options but doesn’t demand expert-level care, this one is worth a serious look. Here’s everything you need to know.

Key Takeaways

• Peaceful schooling fish that does best in groups of 6 or more
• 20-gallon minimum gives a school enough room to swim and display naturally
• Hardy and adaptable to a wide pH range (6.0 to 7.5), making it beginner-friendly
• Distinctive flag-like pattern with a dark horizontal stripe topped by a golden band
• Easy to feed and compatible with most peaceful community fish

Species Overview

Field	Details
Scientific Name	Hemigrammus ulreyi
Common Names	Ulrey’s Tetra
Family	Characidae
Origin	Paraguay River basin, Pantanal region (Brazil/Paraguay)
Care Level	Easy
Temperament	Peaceful
Diet	Omnivore
Tank Level	Mid
Maximum Size	2 inches (5 cm)
Minimum Tank Size	20 gallons (76 liters)
Temperature	72-79°F (22-26°C)
pH	6.0-7.5
Hardness	2-15 dGH
Lifespan	3-5 years in captivity
Breeding	Egg scatterer
Breeding Difficulty	Moderate
Compatibility	Community
OK for Planted Tanks?	Yes

Classification

Taxonomic Level	Classification
Order	Characiformes
Family	Characidae
Genus	Hemigrammus
Species	H. ulreyi (Boulenger, 1895)

The genus Hemigrammus is one of the largest in the order Characiformes, containing over 70 described species. Taxonomy within the genus is considered Incertae Sedis (uncertain placement), and future revisions may reorganize several species into new genera.

Note on taxonomy: In 2024, a major phylogenomic study (Melo et al.) reorganized the traditional family Characidae, splitting several genera into newly erected families. Unlike many other Hemigrammus species that were moved into Acestrorhamphidae, H. ulreyi remained within Characidae based on its phylogenetic placement. Some older references may group it differently, but current evidence supports keeping it in Characidae.

Origin & Natural Habitat

Ulrey’s tetra is native to the Paraguay River basin, including the vast Pantanal wetlands that span parts of Brazil and Paraguay. The Pantanal is one of the largest tropical wetland systems on Earth, and it provides a unique environment shaped by dramatic seasonal flooding.

In the wild, these fish inhabit slow-moving streams, tributaries, and floodplain pools where vegetation is dense along the margins. The water is typically warm, slightly acidic to neutral, and moderately soft. The substrate is often sandy or silty, with leaf litter and submerged vegetation providing cover. During the wet season, flooded grasslands and forests expand the available habitat significantly, and these tetras take advantage of the additional food sources and shelter.

Understanding this environment is helpful when setting up a tank for them. They don’t come from extreme blackwater conditions, so they’re more adaptable to typical aquarium water than many other South American tetras.

Appearance & Identification

Ulrey’s tetra is a clean-looking fish with a distinctive color pattern that makes it easy to identify once you know what to look for. The body is a silvery olive base, compressed laterally like most characins. What sets it apart is the bold dark horizontal stripe that runs from behind the gill cover to the base of the tail fin.

Just above that dark stripe sits a bright golden-yellow band that runs parallel to it, creating a striking two-toned “flag” pattern. This contrast between the dark and golden markings is the hallmark of the species and gives the fish a polished, well-defined look that really pops in a planted tank.

The fins are mostly transparent with a slight yellowish tint. The upper portion of the eye shows the reddish tone that’s common in many Hemigrammus species. In good conditions with proper lighting and diet, the colors intensify noticeably, and a well-maintained school is genuinely attractive.

Male vs. Female

Sexual dimorphism in Ulrey’s tetras is subtle. Males are typically slimmer and may display slightly more vivid coloration, especially along the golden band. Females tend to be rounder and fuller-bodied, particularly when they are carrying eggs. The differences are most visible when comparing adults side by side, but they aren’t dramatic enough to spot at a glance in a mixed group.

Average Size & Lifespan

Ulrey’s tetras reach a maximum size of about 2 inches (5 cm) in total length. Most aquarium specimens stay in the 1.5 to 1.75 inch range. They’re comparable in size to other popular small tetras like neons and glowlights.

With stable water quality and a varied diet, expect a lifespan of 3 to 5 years. This is typical for small characins. The biggest factors in reaching the upper end of that range are consistent water parameters, proper nutrition, and keeping them in a low-stress environment with appropriate tankmates.

Care Guide

Tank Size

A 20-gallon tank is the recommended minimum for a school of 6 to 8 Ulrey’s tetras. If you want a larger group of 10 or more (which I’d always recommend for schooling species), step up to a 30-gallon or bigger. These fish are active mid-level swimmers, and the extra horizontal swimming space makes a real difference in how naturally the school behaves.

Water Parameters

Parameter	Ideal Range
Temperature	72-79°F (22-26°C)
pH	6.0-7.5
General Hardness	2-15 dGH
KH	2-10 dKH
Ammonia / Nitrite	0 ppm
Nitrate	Below 30 ppm

One of the best things about Ulrey’s tetra is its adaptability. It tolerates a wider pH and hardness range than many South American tetras, which makes it a good fit for hobbyists who don’t have naturally soft water. That said, they’ll show the best coloration in slightly soft, mildly acidic conditions. Adding driftwood or Indian almond leaves to release tannins can help bring out those golden tones.

Filtration & Water Flow

Standard filtration with a hang-on-back filter or sponge filter works well. These fish come from slow-moving waters, so keep the flow moderate. A gentle current is fine, but avoid anything that creates a strong directional flow across the tank. Weekly water changes of 20 to 25 percent will keep nitrates in check and maintain water quality.

Lighting

Moderate lighting is ideal. Ulrey’s tetras aren’t as light-sensitive as some deeper-water species, but they still look their best under subdued conditions. Floating plants like Amazon frogbit or red root floaters help diffuse overhead light and create dappled shade zones that mimic their natural habitat.

Plants & Decorations

A planted tank is the way to go with these fish. Use a mix of background plants (Vallisneria, Amazon swords), midground plants (Cryptocorynes, Anubias), and floating plants to create layers of cover. Driftwood and dried leaf litter add a natural touch and release tannins that enhance coloration.

Leave an open swimming area in the center or front of the tank so the school has room to move together. A well-planted perimeter with open center is the classic community tank layout, and it works perfectly for this species.

Substrate

A dark substrate (black sand, dark gravel, or an aquasoil) will make the golden and dark markings on these fish stand out much more than a light-colored substrate. This isn’t a strict requirement, but the visual difference is significant. Fine sand or smooth gravel both work well.

Tank Mates

Ulrey’s tetras are peaceful community fish that mix well with other calm, similarly sized species. They’re not nippy, not pushy, and generally mind their own business in the mid-water column.

Best Tank Mates

• Other small, peaceful tetras (neon tetras, ember tetras, cardinal tetras, rummy-nose tetras)
• Rasboras (harlequin rasboras, chili rasboras)
• Corydoras catfish
• Small Loricariids (otocinclus, bristlenose plecos)
• Dwarf cichlids (Apistogramma, rams)
• Small gouramis (honey gouramis, sparkling gouramis)
• Peaceful livebearers (endlers, platies)
• Cherry shrimp and amano shrimp
• Nerite snails, mystery snails

Tank Mates to Avoid

• Large or aggressive cichlids (oscars, Jack Dempseys, convicts)
• Fast, nippy species like tiger barbs or serpae tetras
• Any predatory fish large enough to eat them
• Highly territorial bottom-dwellers that may stress the group

Food & Diet

Feeding Ulrey’s tetras is as simple as it gets. They’re true omnivores that accept virtually anything offered. In the wild, they feed on small insects, insect larvae, worms, micro-crustaceans, and plant matter. In the aquarium, variety is the key to keeping them healthy and colorful.

• Staple: High-quality flakes or micro pellets
• Frozen foods: Bloodworms, daphnia, brine shrimp
• Live foods: Baby brine shrimp, microworms, daphnia
• Supplements: Freeze-dried foods, spirulina-based flakes for plant matter

Feed small portions two to three times daily rather than one large feeding. Their mouths are small, so crushed flakes or micro-sized pellets work better than standard pellets. A diet that includes regular frozen or live foods will bring out the best coloration, especially along that golden stripe.

Breeding & Reproduction

Ulrey’s tetras are egg scatterers that can be bred in captivity with proper preparation. They’re not the most frequently bred tetra, but it’s definitely achievable with the right setup and conditioning.

Breeding Difficulty

Moderate. They require a dedicated breeding setup and some preparation, but they don’t have the extreme water chemistry demands of some other characins.

Spawning Tank Setup

• Breeding tank: 10 to 15 gallons
• Decor: Fine-leaved plants (Java moss, Cabomba) or spawning mops
• Lighting: Very dim or cover the sides of the tank
• Filtration: Gentle sponge filter only
• Base: A mesh or marble bottom helps prevent the parents from eating eggs

Water Conditions for Breeding

• Temperature: 78 to 82°F (26 to 28°C), slightly warmer than normal
• pH: 6.0 to 6.5
• Hardness: 2 to 6 dGH (softer water encourages spawning)

Conditioning & Spawning

Condition a breeding pair (or a small group with more males than females) with high-protein live and frozen foods for one to two weeks before introducing them to the breeding tank. Bloodworms, brine shrimp, and daphnia are ideal conditioning foods. Introduce the conditioned fish to the spawning tank in the evening. Spawning typically occurs the following morning as light levels increase.

The female will scatter adhesive eggs among fine-leaved plants or spawning mops. A single spawning can produce 100 to 200 eggs.

Egg & Fry Care

Remove the parents immediately after spawning, as they will eat the eggs. Keep the breeding tank dark, as the eggs are light-sensitive. Eggs typically hatch in 24 to 36 hours. The fry will absorb their yolk sacs over the next 2 to 3 days and become free-swimming around day 4 to 5.

Feed free-swimming fry infusoria or commercially available liquid fry food for the first week, then transition to freshly hatched baby brine shrimp as they grow. Perform small, frequent water changes to maintain quality, and keep the light levels low during the early weeks.

Common Health Issues

Ulrey’s tetras are reasonably hardy fish, but like all small characins, they’re susceptible to a handful of common issues. Most health problems come down to water quality and stress.

Ich (White Spot Disease)

The most common issue with small tetras, usually triggered by temperature swings or transport stress. Look for small white spots on the body and fins. Raise the temperature to 86°F (30°C) gradually and treat with a quality ich medication.

Fin Rot

Typically a water quality problem. Frayed, discolored fin edges are the telltale sign. Increase water change frequency and treat with antibacterial medication if the condition doesn’t improve.

Neon Tetra Disease

A risk with most small characins, caused by the parasite Pleistophora hyphessobryconis. Symptoms include fading color, erratic swimming, and body wasting. There is no reliable cure, so prevention through quarantine is critical. Always quarantine new fish for 2 to 4 weeks before adding them to your main tank.

Stress-Related Illness

Keeping Ulrey’s tetras in groups that are too small, with aggressive tankmates, or in unstable water conditions leads to chronic stress. Stressed fish become more vulnerable to opportunistic infections. The best prevention is a stable environment, proper group size, and compatible tankmates.

Common Mistakes to Avoid

• Keeping too few: A pair or a group of 3 will be stressed and hide constantly. Get at least 6, and 10+ is better.
• Skipping the cycle: These fish should only go into a fully cycled aquarium. They don’t handle ammonia or nitrite spikes well.
• Overly strong flow: They come from calm waters. A powerhead blasting across the tank will exhaust them.
• Aggressive tankmates: They’re peaceful fish that won’t compete with pushy species for food or territory.
• Skipping quarantine: Small tetras are notorious for carrying diseases into established tanks. Always quarantine new arrivals for at least 2 weeks.
• Light-colored substrate with no cover: They’ll look washed out and feel exposed. Give them a dark substrate and plant cover.

Where to Buy

Ulrey’s tetra is not one of the more commonly stocked species at chain pet stores, so you’ll likely need to look at specialty retailers or online fish stores. These are two trusted sources I recommend:

• Flip Aquatics
• Dan’s Fish

Try to buy a group all at once rather than adding individuals over time. A group that arrives together acclimates better and schools more cohesively. If you can’t find them in stock, check back regularly or reach out to the retailer to ask about availability.

Frequently Asked Questions

Are Ulrey’s tetras good for beginners?

Yes. They’re hardy, peaceful, and tolerate a wide range of water parameters. As long as you keep them in a proper group in a cycled tank, they’re a great choice for someone getting into the hobby.

How many Ulrey’s tetras should I keep?

A minimum of 6, but 10 or more is ideal. Larger groups school more naturally, display brighter colors, and are less stressed overall.

Do Ulrey’s tetras nip fins?

No. They’re one of the more peaceful tetra species and are not known for fin nipping behavior. They’re generally safe with long-finned species.

What makes Ulrey’s tetra different from other Hemigrammus species?

The most distinctive feature is the bold dark horizontal stripe with a bright golden-yellow band running just above it. This “flag” pattern is unique to H. ulreyi and makes it easy to distinguish from other small tetras in the genus.

Can Ulrey’s tetras live in hard water?

They’re more adaptable than many South American tetras and can handle moderately hard water up to 15 dGH. However, they’ll show their best colors in softer water. If your tap water is very hard, mixing with RO water can help.

Do Ulrey’s tetras need a heater?

In most homes, yes. They need stable temperatures between 72 and 79°F (22 to 26°C). A reliable heater prevents the temperature swings that can trigger stress and disease.

Closing Thoughts

Ulrey’s tetra is the kind of fish that rewards you for paying attention. It doesn’t have the instant flash of a cardinal tetra or the name recognition of a neon, but a school of 10 or more in a well-planted tank with a dark substrate is a genuinely impressive sight. That golden stripe catches the light in a way that’s hard to appreciate from a single photo.

They’re easy to care for, peaceful with just about everything, and hardy enough to handle typical community tank conditions without issue. If you’ve been keeping the usual small tetras and want to try something a little different, Ulrey’s tetra is a species that deserves a spot on your shortlist.

Recommended Video

Check out our tetra tier list video where we rank the most popular tetras in the hobby, including the Ulrey’s tetra:

References

• Froese, R. and D. Pauly, Eds. FishBase. Hemigrammus ulreyi. Accessed 2025.
• SeriouslyFish. Hemigrammus ulreyi species profile. Accessed 2025.
• Melo, B.F., et al. (2024). Phylogenomics of Characidae. Zoological Journal of the Linnean Society, 202(1), 1-37.

Explore More Tetras

Ulrey’s tetra is just one of dozens of tetra species we cover in our complete species directory. Whether you’re looking for beginner-friendly community tetras or something more specialized, our guide has you covered.

👉 Tetras: Complete A-Z Species Directory