Spotted Blue-Eye (Pseudomugil gertrudae)

Pseudomugil gertrudae, the Spotted Blue-Eye or Gertrude's Blue-Eye, is a miniature rainbowfish native to slow-moving streams, swamps, and forest pools in New Guinea and northern Australia. Growing to only 3–4 cm, it is one of the smallest members of the Pseudomugilidae family. Males are strikingly beautiful, with electric blue irises, a translucent body decorated with rows of iridescent blue-green spots, and elaborate, flowing fins with yellow accents.

This species is a delight for nano aquarium keepers. The males display energetically to each other and females with spread fins and shimmering colors, making them constantly entertaining to observe. Despite their bold displays, they are completely peaceful and too small to threaten any tankmate.

Spotted Blue-Eyes prefer soft to moderately hard, slightly acidic to neutral water with gentle flow and dense planting. Floating plants that diffuse light and fine-leafed plants for cover closely replicate their natural environment. They are surface to mid-water fish that rarely venture to the bottom.

Like all Pseudomugil species, females attach eggs to fine plants or spawning mops. The fry are tiny and require micro foods. Regular spawning can be encouraged by providing fine-leafed plants and maintaining ideal water conditions.

Water Parameters: pH 6.0–7.5, temperature 22–28°C, GH 4–15. Slightly soft to moderately hard water with gentle flow. Avoid strong current and dramatic temperature fluctuations. Regular water changes of 20–25% weekly maintain water quality in nano setups.

Tank Setup: A 30–40 liter nano aquarium for a group of 6–10. Dense fine-leafed plants (Java moss, hornwort, guppy grass), floating plants, and a dark substrate create ideal conditions. Gentle sponge filtration is perfect. Avoid powerful filters that create strong currents.

Feeding: Accept micro flake food, micro pellets, baby brine shrimp, micro worms, and daphnia. Feed twice daily in very small amounts appropriate to their tiny size. Variety in diet enhances male coloration and display intensity.

Tankmates: Compatible with other tiny, peaceful nano fish: microrasboras (Boraras sp.), small ricefish, small danios, dwarf shrimp (adults safe). Avoid any fish larger than 5 cm that may intimidate them or compete aggressively for food.

Breeding: Females lay eggs on fine plants or spawning mops. Collect eggs and hatch in a separate vessel. Fry require infusoria and micro-brine shrimp nauplii. Regular spawning in appropriate conditions.