Care Requirements
Adult Size
2.4" (6cm)
Min Tank
20 gal
Temperature
68-79°F
pH Range
6-7.5
Lifespan
5-7 years
Min Group
6+ fish
Diet
Omnivore
Swim Level
Middle
Bioload
2/10
Hardness
4-18 dGH
About Black Skirt Tetra
The Black Skirt Tetra is one of the most recognizable and hardy tetras in the freshwater aquarium hobby. Also known as the Black Widow Tetra or Petticoat Tetra, these distinctive fish feature a dramatic flowing anal fin and striking dark coloration that makes them stand out in any community tank.
They're exceptionally hardy and adaptable, tolerating a wide range of water conditions that would stress more delicate species. This resilience makes them excellent beginner fish—they're forgiving of the mistakes new hobbyists inevitably make while learning. Their willingness to eat virtually any food and adapt to various tank conditions has made them a staple of the hobby for decades.
One important caveat: Black Skirt Tetras can be fin nippers, particularly if kept in small groups or with tempting long-finned tankmates like bettas or fancy guppies. Keeping them in groups of 6 or more significantly reduces this behavior, as they focus their attention on each other rather than tankmates. They're also the base species for the popular GloFish tetras—genetically modified versions that fluoresce under blue light.
Natural Habitat & Origin
Black Skirt Tetras originate from South America, specifically the Paraguay, Guapore, and Bolivia river basins. They inhabit slow-moving tributaries, streams, and flooded forest areas with dense vegetation and shaded conditions.
Their natural habitat features soft, slightly acidic water with abundant plant cover providing security and shade. This explains their preference for subdued lighting and planted tanks in aquarium settings, though captive-bred specimens adapt readily to a wide range of conditions.
Native Region
South America—Paraguay, Guapore, and Bolivia river basins
Habitat Type
Slow-moving tributaries, streams, and flooded forests
Wild Water Conditions
Soft, slightly acidic, shaded areas with dense vegetation
Appearance & Varieties
Black Skirt Tetras are medium-sized tetras reaching about 3 inches (7.5 cm). Their most distinctive feature is the large, flowing black anal fin that resembles a 'skirt' or petticoat—hence their common names. The body is laterally compressed with two prominent vertical black bars.
Juveniles display deep black coloration, but this naturally fades to gray as they age—a process that surprises many new keepers. By 1-2 years old, most specimens have faded significantly. This is normal and not a sign of poor health. Males tend to be slimmer with more pointed dorsal fins, while females are rounder with a white edge on the anal fin.
Popular Varieties
| Variety | Description | Rarity |
|---|---|---|
| Wild Type | Standard black/gray coloration with flowing black fins | Very Common |
| Long-finned | Extended finnage—even more dramatic flowing appearance | Common |
| GloFish Tetra | Genetically modified to fluoresce in various colors | Common |
| White Skirt | Leucistic variant—white/cream coloring | Common |
| Colored/Dyed | Artificially dyed—colors fade, harmful practice, avoid | Common |
Tank Setup & Requirements
Quick Requirements Summary
Tank Size
Minimum Tank Size
20 gallons
Recommended Tank Size
30 gallons
Black Skirt Tetras need at least 20 gallons (75 liters) for a school, with 30 gallons (115 liters) being preferable for a larger group and additional tankmates. Long tanks are better than tall ones to provide swimming length.
Water Parameters
Highly adaptable: temperature 72-82°F (22-28°C), pH 6.0-8.0, GH 5-20. They tolerate a remarkably wide range, making them excellent for beginners. Stability matters more than hitting exact numbers.
Substrate
Any substrate works. Dark substrates enhance their coloring, though as they age and fade to gray, this becomes less dramatic.
Plants & Decorations
Plants are beneficial, providing cover and a natural feel. Create a layout with open swimming areas in the center and planted perimeters. Floating plants provide appreciated shade.
Filtration & Water Flow
Standard filtration with moderate flow is fine. They're not demanding and adapt to most common filter setups.
Lighting
Moderate to subdued lighting enhances their dark coloration. Very bright lighting can wash them out and stress them.
Diet & Feeding Guide
Diet Type
omnivore
Feeding Frequency
1-2x daily
Portion Size
What they consume in 2-3 minutes
Black Skirt Tetras are enthusiastic omnivores that accept virtually any aquarium food. This unfussy appetite is part of what makes them such easy fish to keep—they rarely refuse a meal.
Best Foods for Black Skirt Tetra
- High-quality flakes — Staple diet—they eat flakes readily
- Micro pellets — Good sinking option for variety
- Frozen bloodworms — Favorite treat, enhances color
- Frozen brine shrimp — Excellent protein supplement
- Daphnia — Good live/frozen food option
- Blanched vegetables — Occasional variety
Foods to Avoid
- Large pellets — Too big for their mouths
- Low-quality foods with fillers — Poor nutrition, can cause digestive issues
They're enthusiastic eaters and will accept nearly any food offered. Varied diet keeps them healthy and enhances color. Feed amounts they can consume in 2-3 minutes.
Behavior & Temperament
Black Skirt Tetras are active mid-water swimmers that establish loose schools with minor hierarchies. They chase each other occasionally, but this is normal social behavior rather than aggression.
The fin-nipping reputation is deserved but context-dependent. In small groups, they may nip tankmates' fins, especially if those tankmates have long, flowing finnage that proves irresistible. In larger groups (6+), they primarily focus on each other, significantly reducing nipping of other species. Choose tankmates wisely and you'll avoid problems.
Note that their black coloration fades with age—juveniles are dramatically dark, but adults gradually fade to gray/silver over 1-2 years. This is completely normal and not a sign of illness or poor conditions.
Tank Mates: Compatibility Guide
Compatible Tank Mates
Similar species, good companions
Different level, peaceful coexistence
Similar size and temperament
Fast-moving, not tempting targets
Robust and active
Rainbowfish
Active, similarly sized
Different level, ignore each other
Tank Mates to Avoid
Bettas
Long fins are irresistible nipping targets
Fancy Guppies
Flowing fins will be nipped
Angelfish
Long fins, slow movement—will be harassed
Very small fish
May be bullied
Slow-moving fish
Easy targets for nipping
Common Pairing Questions
Do black skirt tetras nip fins?
They can, especially if kept in small groups or with tempting targets like bettas or fancy guppies. Keep them in groups of 6+ and avoid long-finned tankmates to minimize nipping.
Can I keep black skirt tetras with bettas?
Not recommended. Black skirt tetras are known fin nippers and betta fins are irresistible targets. This combination almost always ends with a stressed, damaged betta.
Are GloFish tetras the same as black skirt tetras?
Yes—GloFish tetras are genetically modified black skirt tetras with fluorescent genes. They have identical care requirements but glow under blue/UV light.
Black Skirt Tetras are among the easiest tetras to breed in home aquariums. They're egg scatterers that spawn readily with minimal encouragement.
Set up a breeding tank with fine-leaved plants or spawning mops, slightly warmer water, and dim lighting. Condition breeders with high-quality foods for a week or two before spawning attempts. Males chase females, and eggs are scattered among plants—300-500 eggs is typical.
Remove parents immediately after spawning as they will eat eggs. Eggs hatch in 24-36 hours and fry become free-swimming a few days later. Feed infusoria initially, transitioning to baby brine shrimp after a week. Eggs and fry are light-sensitive.
Health Issues & Disease Prevention
Black Skirt Tetras are exceptionally hardy—one of the most resilient tetras available. They tolerate water quality issues that would stress more delicate species, though this doesn't mean you should neglect their care.
Common Diseases
| Disease | Symptoms | Treatment |
|---|---|---|
| Ich | White spots, scratching on objects | Raise temperature, standard ich medication |
| Fin rot | Frayed, deteriorating fins | Improve water quality, antibacterial treatment if severe |
| Velvet | Gold dust appearance, lethargy | Copper-based medication, dim lighting |
| Columnaris | White patches, mouth fungus | Antibacterial treatment, improve water quality |
Signs of a Healthy Black Skirt Tetra
- Active swimming in mid-water
- Good appetite
- Schooling with group
- Intact, full fins
- Dark coloration (in juveniles)
Prevention Tips
- Quarantine new fish for 2 weeks before adding to main tank
- Maintain stable water parameters
- Keep in groups of 6+ to reduce stress
- Avoid tankmates that will nip their fins
- Provide varied diet for optimal health
Frequently Asked Questions
Color fading is natural with age. Juveniles are jet black, but adults gradually fade to gray/silver over 1-2 years. Stress, poor water quality, and bright lighting can also cause fading.
They can, especially if kept in small groups or with tempting targets like bettas or fancy guppies. Keep them in groups of 6+ and avoid long-finned tankmates to minimize nipping.
Yes—GloFish tetras are genetically modified black skirt tetras with fluorescent genes. They have identical care requirements but glow under blue/UV light.
No—they're schooling fish that need groups of 6+ to feel secure and behave naturally. Solitary fish become stressed, hide, and may become aggressive.
Tips for Keeping Black Skirt Tetra
Pro Tips
- ✓Keep 6+ to minimize fin-nipping behavior
- ✓They're one of the hardiest tetras—perfect for beginners
- ✓Expect color to fade as they age—it's normal
- ✓Dark substrate and subdued lighting enhance their appearance
- ✓They're the base species for GloFish tetras
- ✓Avoid pairing with bettas, angelfish, or fancy guppies
- ✓One of the easiest tetras to breed
Common Mistakes to Avoid
- ✗Keeping with long-finned fish—will nip fins
- ✗Small groups—increases aggression and nipping
- ✗Expecting jet black color in adults—they fade naturally
- ✗Very bright lighting—washes out coloration
- ✗Keeping alone—they need schools
- ✗Keeping with slow, docile fish
Sources
- FishBase — Accepted scientific name, maximum size and native range for Black Skirt Tetra.
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