Gertrude’s Spotted Blue Eye Rainbowfish (Pseudomugil gertrudae) is a dazzling nano fish species native to Australia and New Guinea. Known for its electric blue eyes and spotted fins, it’s a favorite among aquascaping enthusiasts and nano tank keepers. 

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Species Overview

• Scientific Name: Pseudomugil gertrudae
• Common Names: Gertrude’s Rainbowfish, Spotted Blue Eye Rainbowfish
• Size: 2.5–4 cm (1–1.5 inches) 
• Lifespan: 3–5 years
• Temperament: Peaceful, but males can be mildly territorial
• Shoaling: Best kept in groups of 6–10+

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Appearance

• Body: Semi-transparent silver-blue with a golden sheen
• Eyes: Bright electric blue
• Fins: Clear to yellowish with orange/red tips and black spots
• Males: More colorful with elongated fins and intense spotting during breeding 

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Tank Setup

• Minimum Tank Size: 10 gallons
• Water Temperature: 72–82°F (22–28°C)
• pH: 6.5–7.5
• Hardness: Soft to moderately hard
• Substrate: Dark sand or gravel to enhance colors
• Décor: Driftwood, leaf litter, caves, and dense live plants like Java Fern, Anubias, and Water Wisteria 
• Filtration: Gentle flow; avoid strong currents
• Lighting: Moderate

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Diet

• Type: Omnivore
• Preferred Foods:
  • Live/frozen: Brine shrimp, daphnia, bloodworms
  • Dry: Micro pellets, high-quality flakes
  • Plant-based: Algae flakes, blanched veggies
• Feeding Frequency: 2–3 times daily in small portions 

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Tank Mates

Ideal companions include:

• Neon Tetras
• Ember Tetras
• Celestial Pearl Danios
• Pygmy Corydoras
• Cherry Shrimp
• Otocinclus Catfish

Avoid:

• Large or aggressive fish
• Fast swimmers that may outcompete them

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Breeding

• Method: Egg scatterers
• Setup: Separate breeding tank with fine-leaved plants or spawning mops
• Spawning: Males court females with color displays; eggs are laid and scattered
• Fry Care:
  • Feed infusoria or powdered fry food initially
  • Transition to baby brine shrimp after 5 days
  • Remove adults post-spawning to prevent predation

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