Information, Freshwater fish, Rainbowfish, Species

Spotted Blue-eye (Pseudomugil gertrudae)

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by Jason Matthews



The Spotted blue-eye is well-known for its vibrant colors and distinctive markings, making it a popular pet fish choice. Whether you’re a new or experienced pet fish owner, this article will teach you everything you need to know about the Spotted blue-eye.

This article will cover everything you need to know about this beautiful fish species, from its origin and appearance to its behavior and tank conditions. So, sit back, grab a cup of tea, and join us as we dive into the world of the Spotted blue-eye.


Scientific Name: Pseudomugil gertrudae
Common Names: Gertrude`s Blue-eye Rainbowfish
Life Expectancy: 3-5 years
Adult Size: 3.8 cm (1 ½ inches)


HabitatFreshwater streams and swamps
Care LevelIntermediate
DietOmnivorous – Small live and frozen foods, as well as high-quality flake and pellet foods
Tank LevelMid-level
Minimum Tank Size10 gallons (38 liters)
Water pH6.0-7.5
Water Temperature72-82°F (22-28°C)
Water HardnessSoft to slightly hard
Tank MatesPeaceful community fish, preferably small and non-aggressive species

Fun Fact Corner

Spotted blue-eyes are known for their unique and fascinating courtship display. Male Spotted blue-eyes swim in circles and flash their blue and orange colors to attract females during mating season. This display is visually appealing and serves to attract a mate and show dominance over other males.


The Spotted blue-eye, also known as the Blue-eye rainbowfish, is a freshwater fish native to Australia’s rivers and streams. This species is most common in Australia’s Northern Territory, including the coastal regions of Queensland and the Northern Territory. The Spotted blue-eye belongs to the Melanotaeniidae family, including other rainbowfish species.

Appearance & Size

The Spotted blue-eye is named after a bright blue iridescent spot on its eye, which gives it the name “spotted blue-eye.” The Spotted blue-eye has a bright blue body with iridescent scales that shimmer in the light. Additionally, this species has distinctive markings that are either black or yellow and are arranged in a unique pattern along its body. The fins of the Spotted blue-eye are also colored, with the dorsal fin being bright red and the anal fin being yellow. The pectoral fins of the Spotted blue-eye are also a vibrant blue color and are often tipped with black.

The Spotted blue-eye is a relatively small species of fish, with adults typically reaching sizes of 1.5 inches long. This makes it an ideal choice for smaller aquariums, as it only requires a small amount of space to thrive. It is important to note that the size of the Spotted blue-eye can vary depending on the environment and diet, so it is essential to provide it with the proper conditions to reach its full potential.


The Spotted blue-eye is a fish species that exhibit sexual dimorphism, which means that males and females look very different. Male Spotted blue-eyes are larger and brighter in color than females, and they have longer dorsal and anal fins. Male Spotted blue-eyes also have a more pointed and triangular dorsal fin than females, which is more rounded.


The Spotted blue-eye is a highly active fish known for its lively behavior in the aquarium. This species is a strong swimmer, constantly moving, exploring its surroundings, and looking for food. They are also active jumpers and have been known to escape from tanks that have not been properly secured.


Spotted blue-eyes are not aggressive towards other fish and are best kept in a community tank with peaceful, similarly-sized species. 

Good tankmates for Spotted blue-eyes include:

  • Other temperate species of small, brightly-colored fish, such as Neon tetras and Guppies
  • Shrimp species such as cherry shrimp and ghost shrimp
  • Snails such as Nerite snails and Mystery snails
  • Other species of small, non-aggressive fish such as Rasboras and Dwarf Gouramis

Tank conditions

The Spotted blue-eye is a hardy fish that can adapt to various aquarium conditions. However, providing them with a tank environment that resembles their natural habitat is critical to maintaining optimal health and longevity. 

This species is native to Australia and New Guinea’s slow-moving streams and ponds. It prefers a tank environment with gentle water flow and plenty of hiding places. A well-planted tank with plenty of vegetation and other natural decorations can provide hiding places for Spotted blue eyes and help reduce stress levels. 

Furthermore, this species prefers a slightly acidic to neutral pH range of 6.0 to 7.5 and water temperatures ranging from 72 to 78°F. Good filtration and regular water changes are essential for keeping Spotted blue-eyes in a healthy and stable tank environment.


The Spotted blue-eye is an omnivorous species that requires a varied diet. In their natural habitat, they eat various small insects, crustaceans, and plant matter. A staple diet of high-quality dry flake or pellet food can be supplemented with occasional feedings of live or frozen food such as brine shrimp, bloodworms, and daphnia. Vegetable matter such as blanched spinach or lettuce can also be offered to provide additional nutrients and variety.

It is critical to avoid overfeeding Spotted blue-eyes because excess food can cause water quality issues and harm the fish’s health. A general rule of thumb is to feed the fish only as much food as they can consume in a few minutes, 2-3 times per day.


Breeding Spotted blue-eyes can be a rewarding experience for experienced aquarium hobbyists. While they are not considered challenging to breed, some knowledge of their biology and breeding requirements is necessary to ensure success.

To breed Spotted blue-eyes, optimal water conditions are required, including a stable temperature of 75-82°F, a pH of 7.0-8.0, and a hardness of 5-19 dGH. A breeding tank with plenty of hiding places and a dense planting of Java moss or another suitable substrate should also be established.

Once the conditions are right, a group of Spotted blue-eyes can be introduced to the breeding tank. It is best to keep a ratio of one male to two or three females, as the males can become aggressive toward each other when breeding. The females will lay their eggs in the dense planting, and the males will fertilize them.

After breeding, the parents should be removed from the breeding tank to prevent them from eating their eggs. The eggs will hatch in 2-3 days, and the fry can be fed with small live foods such as newly hatched brine shrimp or microworms. As the fry grows, it can be gradually weaned onto dry food.


The spotted blue-eye is a hardy species and is not prone to many illnesses. However, as with any other fish species, it is critical to maintain proper tank conditions to ensure your fish’s health. Fin rot, ich, and parasitic infections are some of the most common diseases that Spotted blue-eye may encounter. It’s also important to look out for symptoms like loss of appetite, clamped fins, and unusual swimming behavior.

Keep the tank water clean and well-maintained to prevent disease transmission. Regular water changes and proper filtration will help keep your fish’s tank environment healthy. Additionally, it is recommended to quarantine any new fish before adding them to your tank to prevent the spread of any diseases from new arrivals. If you suspect your fish is sick, consult with a veterinarian specializing in aquarium fish to determine the best course of treatment.


Jason Matthews

My name is Jason Matthews, and welcome to my website. When other kids were bragging about how their dog could sit and roll over, I was bragging about my latest Betta Fish and the cool sea castle I just added to his aquarium. 

Jason aquariume

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