Gertrude's Spotted Blue Eye Rainbowfish - "Getrudae Rainbowfish" by Atulbhats is licensed under CC BY-SA 4.0.
Gertrude's Spotted Blue Eye Rainbowfish - "Getrudae Rainbowfish" by Atulbhats is licensed under CC BY-SA 4.0.


In the enchanting world of freshwater aquaria, Gertrude’s Spotted Blue Eye Rainbowfish emerges as a jewel among small fish species. Native to the tranquil streams and waterways of Australia and New Guinea, this diminutive yet vibrant creature captivates with its dazzling colors and spirited demeanor. Perfect for aquarists, this blue eye rainbowfish, with its iridescent hues and playful antics, offers a window into the lush, underwater tapestry of its native habitats. This article delves into the essentials of creating an ideal environment for these delightful fish, ensuring they not only survive but thrive in home aquariums, bringing a splash of nature’s brilliance into our lives.

Appearance of Gertrude’s Spotted Blue Eye Rainbowfish

Gertrude’s Spotted Blue Eye Rainbowfish (Pseudomugil gertrudae) is a small, visually striking species known for its vibrant colors and unique features. In terms of physical appearance and characteristics, here are some key aspects:

  • Size: This species is relatively small, typically reaching only about 3 to 4 centimeters (1.2 to 1.6 inches) in length. This petite size makes it a popular choice for smaller aquariums.
  • Body Shape: They have a slender, elongated body shape typical of many rainbowfish. This streamlined form is well-adapted for quick, darting movements in water.
  • Coloration: One of the most striking features of Gertrude’s Spotted Blue Eye is its coloration. These fish display a base color of translucent silver or pale blue. The body is adorned with a series of spots or short lines, which can be black, blue, or green, depending on the light and the individual fish.
  • Fins: The fins of Gertrude’s Spotted Blue Eye Rainbowfish are delicate and nearly transparent, with some individuals exhibiting subtle hints of yellow, orange, or red on the edges of their dorsal and anal fins. The caudal (tail) fin is typically fan-shaped with a clear or lightly colored base and darker edges.
  • Eyes: True to its name, this species has distinctive bright blue eyes, which are not only visually striking but also serve as a key identifying feature. The vivid blue iris stands out remarkably against the more subdued body color.
  • Distinctive Features: Compared to other rainbowfish species, this blue eye rainbowfish is distinguished by its smaller size, the unique spotted or striped patterns, and its bright blue eyes. These features set them apart in an aquarium setting, where they can often be seen actively swimming in the upper to middle layers of the water.

Their vibrant appearance and dynamic swimming behavior make them a captivating species for both novice and experienced aquarium enthusiasts. When kept in groups, the social interactions and the enhanced coloration of the males, especially during breeding displays, add to their appeal.

Diet and Feeding

Gertrude’s Spotted Blue Eye Rainbowfish have specific dietary preferences and feeding habits that are important for their health and well-being, both in the wild and in aquarium settings.

In the Wild

  • Natural Diet: In their natural habitats, these fish are omnivores but lean towards a carnivorous diet. They primarily feed on small invertebrates such as insects, larvae, small crustaceans, and zooplankton found in and around aquatic vegetation.
  • Feeding Behavior: They are adept at picking food items from the water column and the surface. Their feeding strategy involves quick, darting movements to catch prey, reflecting their active and agile nature.

In Aquariums

  • Variety is Key: In captivity, it’s crucial to replicate their natural diet as closely as possible. A varied diet that includes both plant and animal matter is ideal.
  • Live and Frozen Foods: Live foods such as brine shrimp, daphnia, and bloodworms are excellent choices that mimic their natural prey. Frozen varieties of these foods can also be used as a convenient alternative.
  • Dry Foods: High-quality flake foods or micro pellets designed for small, omnivorous fish can be a staple in their diet. However, these should be supplemented with live or frozen foods for optimal health.
  • Vegetation: Including some plant-based foods or algae-based flakes can provide the necessary vegetable matter. This is especially important if the aquarium lacks live plants.
  • Feeding Frequency and Amount: Small, frequent feedings are recommended. Two to three times a day in small amounts that they can consume within a few minutes is ideal. Overfeeding should be avoided to maintain water quality.
  • Observation: Regular observation during feeding times can help assess their health and vigor. It also provides an opportunity to ensure that all fish are getting an equal chance to feed, which is important in a community tank setting.
  • Water Quality and Diet: Good water quality is essential for the health of these fish. A well-maintained tank and a balanced diet help in enhancing their coloration and overall health.

By providing a diet that closely resembles their natural feeding habits, these blue eye rainbowfish will thrive in an aquarium setting, displaying their natural behaviors and vibrant colors. Regular monitoring and adjustments to their diet, based on their specific needs and the conditions of the aquarium, are key to maintaining their health and well-being.

Tank Mates for Blue Eye Rainbowfish

Choosing compatible tank mates for Gertrude’s Spotted Blue Eye Rainbowfish is crucial for maintaining a harmonious and healthy aquarium. This species is generally peaceful and can coexist with a variety of other fish, provided their environmental and behavioral needs are compatible. Here are some guidelines and suggestions for selecting tank mates:

Key Considerations

  • Temperament: Choose tank mates that are similarly peaceful. Aggressive or overly active fish might intimidate or outcompete the rainbowfish for food.
  • Size: Select fish that are similar in size. Larger fish might see Gertrude’s Spotted Blue Eye as prey, while much smaller fish could be stressed by their relatively more active behavior.
  • Water Conditions: Ensure that the tank mates you select thrive in similar water conditions (temperature, pH, hardness) as this blue eye rainbowfish.
  • Swimming Regions: Consider fish that occupy different levels of the tank to avoid overcrowding any one area. Gertrude’s Spotted Blue Eye Rainbowfish typically swims in the middle to upper levels of the aquarium.

Suitable Tank Mates

  1. Other Rainbowfish: Smaller species of rainbowfish can be good companions, as they share similar habitats and behaviors.
  2. Tetras: Many smaller tetra species, such as neon tetras or cardinal tetras, can be a good fit. They are peaceful and share similar water requirements.
  3. Rasboras: Small rasboras are a good match in terms of size and temperament. harlequin rasboras, for example, can be a colorful and active addition.
  4. Dwarf Gouramis: These are peaceful and add a different shape and style to the tank. However, ensure they are not overly territorial.
  5. Corydoras: These bottom dwellers are peaceful and can add activity to the lower levels of the tank.
  6. Shrimps and Snails: Various freshwater shrimps (like cherry shrimp) and snails can coexist with Gertrude’s Spotted Blue Eye Rainbowfish and also help in keeping the tank clean.

Tank Mates to Avoid

  • Large or Aggressive Fish: Avoid large, predatory fish or known fin-nippers like some barbs and larger cichlids.
  • Very Small, Shy Fish: Extremely small or shy species might be outcompeted for food or stressed by the more active rainbowfish.

General Tips

  • Observation: After introducing new tank mates, monitor the tank closely to ensure all species are coexisting peacefully and that there’s no bullying or stress.
  • Gradual Introduction: Introduce new fish gradually to avoid overwhelming the existing inhabitants and to monitor compatibility.
  • Aquarium Size: Ensure your tank is large enough to accommodate the combined bioload of all species and provide adequate space for each.

By carefully selecting tank mates that are compatible in size, temperament, and environmental needs, you can create a diverse, colorful, and peaceful community aquarium that suits Gertrude’s Spotted Blue Eye Rainbowfish.

Gertrude's Spotted Blue Eye Rainbowfish - "Getrudae Rainbowfish" by Atulbhats is licensed under CC BY-SA 4.0.
Gertrude’s Spotted Blue Eye Rainbowfish – “Getrudae Rainbowfish” by Atulbhats is licensed under CC BY-SA 4.0.

Aquarium Setup

Setting up an aquarium for Gertrude’s Spotted Blue Eye Rainbowfish requires attention to several key aspects to create an environment that closely mimics their natural habitat. This will not only ensure their health and well-being but also bring out their best colors and behaviors. Here’s a guide to setting up their aquarium:

Tank Size

  • Minimum Size: A minimum of 10 gallons (40 liters) is recommended for a small group. These fish are active swimmers and appreciate space.
  • Group Size: They are best kept in groups of at least 6-10, as they are schooling fish and thrive in social environments.

Water Conditions

  • Temperature: Maintain the water temperature between 75-80°F (24-27°C).
  • pH Level: Aim for a pH level of 6.5 to 7.5, slightly acidic to neutral.
  • Water Hardness: Soft to moderately hard water is preferable.
  • Filtration: Use a good-quality filter to keep the water clean. However, ensure the water flow is not too strong as they prefer gentler currents.
  • Regular Water Changes: Perform regular water changes, about 20-25% weekly, to maintain water quality.

Tank Layout

  • Plants: Dense planting is recommended to mimic their natural environment. Live plants like Java Fern, Anubias, and Water Wisteria provide hiding places and maintain water quality.
  • Substrate: A dark substrate can help in showcasing their colors. Sand or fine gravel works well.
  • Decorations: Include driftwood, rocks, or caves to provide additional shelter and replicate natural structures.
  • Lighting: Moderate lighting is preferred to encourage plant growth and display the fish’s natural colors without being too intense.

Feeding Zone

  • Designate an area for feeding where the fish can easily access food without it being trapped in the decorations or substrate.


  • Regular monitoring of water parameters is essential to detect any changes in pH, temperature, or ammonia levels.
  • Ensure the tank is cycled properly before introducing the fish.
  • Clean the tank regularly, but avoid complete overhauls as this can disrupt the beneficial bacteria and stress the fish.

Additional Tips

  • Acclimation: When introducing Gertrude’s Spotted Blue Eye Rainbowfish to the tank, acclimate them slowly to the tank conditions.
  • Avoid Overcrowding: Give them enough space to swim and exhibit natural behaviors.

By following these guidelines, you can create a healthy, visually appealing habitat for Gertrude’s Spotted Blue Eye Rainbowfish, allowing them to thrive and exhibit their natural beauty and behavior.


Gertrude’s Spotted Blue Eye Rainbowfish, a gem in the realm of freshwater aquariums, is more than just a visually stunning species. Its care and maintenance offer an engaging journey into aquatic care, blending aesthetics with the rewarding challenge of replicating a natural ecosystem. By attentively crafting their habitat, from the lushness of live plants to the stability of water parameters, aquarists are rewarded with a vibrant display of natural behavior and beauty. These fish are not just pets; they are ambassadors of their native environments, teaching us about the delicate balance of aquatic ecosystems. In nurturing them, we gain not only a serene underwater spectacle but also a deeper appreciation for the intricate tapestry of life that thrives beneath the water’s surface.