GloFish® Cosmic Blue® Tetra

The GloFish® Cosmic Blue® Tetra is a vivid freshwater schooling fish with bright fluorescent blue coloration. It combines the active swimming behavior and deep-bodied shape of a skirt tetra with the distinctive Cosmic Blue® appearance of the GloFish line.

Cosmic Blue® Tetras are colorful under standard white aquarium lighting and become especially vibrant under blue LED lighting. GloFish® fluorescent fish are not painted, injected, or artificially dyed. Their coloration is inherited and remains with them throughout their lives.

Key Features

• Bright Cosmic Blue® fluorescent coloration
• Freshwater schooling community fish
• Active midwater swimmer
• Color appears bright under white light and especially vivid under blue LEDs
• Not painted, injected, or artificially dyed
• Best kept in a group of compatible skirt tetras
• Suitable for established tropical community aquariums
• Can school with other GloFish® tetra colors and standard skirt tetras

Fish Information

• Common Name: GloFish® Cosmic Blue® Tetra
• Fish Type: Fluorescent skirt tetra
• Water Type: Freshwater
• Temperament: Generally peaceful and active
• Adult Size: Approximately 2–2.5 inches
• Recommended Group Size: At least 6 compatible skirt tetras
• Recommended Minimum Tank Size: 20 gallons for a group
• Swimming Level: Middle of the aquarium
• Diet: Omnivore

Recommended Water Parameters

• Temperature: Approximately 72–80°F
• pH: Approximately 6.5–7.5
• Water Hardness: Soft to moderately hard
• Ammonia: 0 ppm
• Nitrite: 0 ppm
• Nitrate: Kept as low as practical through regular maintenance

Stable water quality is more important than reaching one exact pH or hardness value. Avoid sudden changes in temperature or water chemistry.

Schooling and Behavior

Cosmic Blue® Tetras are social schooling fish and should not be kept alone. Maintain a group of at least six compatible skirt tetras, with a larger group preferred when aquarium space allows.

Different GloFish® skirt tetra colors can generally be combined in the same school. Standard black skirt and white skirt tetras may also be kept with them because they share similar behavior and care requirements.

Skirt tetras may occasionally chase or nip, particularly when kept in groups that are too small. A properly sized school, adequate swimming room, and planted areas can help encourage more natural social behavior.

Aquarium Setup

Provide a fully cycled, heated, and filtered freshwater aquarium with open swimming space through the middle. Plants and aquarium-safe décor can be arranged along the sides and back to provide shelter without restricting movement.

• Use a properly cycled aquarium
• Provide reliable filtration and good oxygenation
• Leave open space for schooling and swimming
• Add live or artificial plants for cover
• Use a secure aquarium lid
• Perform routine partial water changes
• Maintain a regular day-and-night lighting schedule

Lighting

Cosmic Blue® Tetras remain colorful under standard white aquarium lighting. Blue LED lighting can make their fluorescent blue coloration appear especially vivid.

Do not leave aquarium lights on continuously. Provide a normal period of darkness each day so the fish can rest.

Compatible Tankmates

Choose peaceful, similarly sized community fish that prefer comparable tropical water conditions.

• Other GloFish® skirt tetras
• Standard black or white skirt tetras
• Peaceful rasboras
• Danios
• Corydoras catfish
• Small to medium peaceful barbs
• Peaceful livebearers
• Appropriately sized peaceful gouramis
• Other non-aggressive community fish

Avoid highly aggressive fish, species large enough to eat them, and very timid or long-finned tankmates that may be stressed or nipped.

Feeding

GloFish® Cosmic Blue® Tetras are omnivores and should receive a varied diet of appropriately sized foods.

• Quality tropical flakes
• Small floating or slow-sinking pellets
• Frozen brine shrimp
• Frozen daphnia
• Frozen or freeze-dried bloodworms as an occasional food

Feed a small amount once or twice daily. Offer only what the fish can consume within a few minutes and avoid allowing excess food to accumulate in the aquarium.

Acclimation

1. Turn off the aquarium lights before introducing the fish.
2. Float the unopened transport bag for approximately 15–20 minutes to equalize temperature.
3. Gradually add small amounts of aquarium water to the bag or acclimation container.
4. Carefully net the fish into the aquarium.
5. Avoid pouring transport water into the display aquarium when practical.
6. Leave the aquarium lights off for several hours while the fish settle.

Quarantine new fish before adding them to an established aquarium whenever a suitable quarantine system is available.

Important Care Notes

• Keep in a school rather than as a single fish.
• Do not add to an uncycled aquarium.
• Maintain stable temperature and water quality.
• Avoid overcrowding and incompatible tankmates.
• Provide a normal light-and-dark cycle.
• Never release aquarium fish into local waterways.

Frequently Asked Questions

Are Cosmic Blue® Tetras dyed?
No. GloFish® fluorescent fish are not painted, injected, or dyed. Their fluorescent coloration is inherited.

Do they need special food or water?
No. Their general care is the same as compatible non-fluorescent skirt tetras. Feed a varied freshwater community fish diet and maintain stable water quality.

Do they glow in complete darkness?
No. Their fluorescent coloration is visible when illuminated and appears especially bright under blue LED aquarium lighting.

Can different GloFish® tetra colors live together?
Yes. Different colors of GloFish® skirt tetras can generally be kept together and count toward the same school.

Can I keep one Cosmic Blue® Tetra alone?
Keeping one alone is not recommended. Maintain at least six compatible skirt tetras together.

Are they suitable for a five-gallon aquarium?
No. They are active schooling fish. A 20-gallon aquarium is a more appropriate starting size for a group.

Will the blue color fade?
The inherited coloration remains with the fish, although its appearance may vary with lighting, health, stress, diet, and aquarium conditions.

Available at Tropical Treasures Wyo

GloFish® Cosmic Blue® Tetras are available at Tropical Treasures Wyo in Cheyenne, Wyoming, when in stock. Live fish are available for in-store purchase or local pickup only and are not available for shipping.

---

Explore More Aquarium Products:

• Shop Freshwater Fish for Sale
• Browse Fish Food for All Aquarium Fish
• Buy Live Aquarium Plants
• Read Aquarium Care Guides & Tips
• Shop Aquarium Filters & Filtration Systems