The Spotted Blue-eye Rainbowfish, scientifically known as Pseudomugil gertrudae, is a small, peaceful, and brilliantly colored freshwater fish native to northern Australia, New Guinea, and nearby islands. It inhabits slow-moving creeks, swamps, and shallow pools, often in areas with dense vegetation and warm, soft water. This species is highly regarded among nano aquarium enthusiasts for its lively schooling behavior, beautiful fin patterning, and ease of care in the right setup. Adults grow to a maximum size of about 1.2 inches (3 cm), making them ideal for smaller tanks. Males are especially eye-catching, with bright blue irises (hence the “blue-eye” name), yellowish-golden body coloration, and boldly spotted dorsal, anal, and caudal fins. Females are generally smaller and more translucent, with more subdued fin markings and less intense color overall. In the aquarium, Pseudomugil gertrudae does best in groups of at least 6 to 10 individuals, as they are shoaling fish and display more natural behavior and coloration when kept in numbers. A tank of 10 to 20 gallons is sufficient for a small group. The environment should be well-planted, with fine-leaved plants, floating cover, and gentle filtration to mimic their natural shallow-water habitat. Water parameters should include a temperature range of 74 to 82°F (23 to 28°C), a pH of 5.5 to 7.5, and soft to moderately hard water. Although adaptable, this species thrives in clean, warm, slightly acidic to neutral water with good surface agitation for oxygenation. Spotted Blue-eyes are micropredators and should be fed a diet of small live and frozen foods such as baby brine shrimp, daphnia, and microworms, along with crushed flakes or micro pellets. Their small mouths require fine food particles, and frequent small feedings are better than large ones. Breeding is relatively straightforward in well-maintained tanks. Males perform elaborate fin displays to attract females. Eggs are typically laid on fine plants or spawning mops, where they adhere via a sticky filament. Spawning may occur daily, and eggs hatch in 7–10 days. Fry are very small and require infusoria or powdered fry food initially before graduating to baby brine shrimp. Overall, Pseudomugil gertrudae (Spotted Blue-eye Rainbowfish) is a delightful species that brings motion, color, and social interaction to nano and planted aquariums. Its peaceful nature and vibrant display make it an excellent choice for hobbyists looking to maintain a vibrant, small-scale biotope or species-focused setup.
