Guppy Moscow Blue

The Moscow Blue Guppy is one of the most coveted and internationally recognized fancy guppy strains, originally developed by Russian guppy breeders and named for the city of Moscow. Males display a rich, deep metallic blue that covers most of the body from head to tail, often with an iridescent quality that intensifies under aquarium lighting. The tail fin is typically large and well-proportioned — fan, veil, or delta shapes are common — displaying matching or complementary blue tones.

The Moscow strain is highly regarded in the competitive guppy breeding community for the depth and uniformity of its metallic coloration, which requires careful selective breeding to maintain. Commercial versions are more variable than show-quality lines, but even standard hobby specimens display impressive blue coloration that catches the eye immediately in a planted tank.

Like all Poecilia reticulata varieties, the Moscow Blue Guppy is a peaceful, social livebearer that adapts readily to a wide range of aquarium conditions. Males display constantly to females and each other, creating a dynamic, colorful display. It shares all the husbandry requirements and reproductive behavior of other fancy guppy strains. The Moscow strain's intense, uniform metallic blue results from an unusually high density of iridophores — specialized reflective cells containing guanine crystals — in the skin, which reflect blue wavelengths particularly efficiently. Maintaining this color quality requires good nutrition (particularly diets with adequate protein and color-enhancing carotenoids), appropriate water conditions, and careful selection of broodstock in each generation.

Tank Setup A 40-liter or larger planted aquarium. Use dark substrate to enhance the metallic blue coloration by contrast. Dense background planting, floating plants for surface cover, and open mid-water swimming space. Gentle sponge or HOB filtration with pre-filter on intake. Heater at 22–28°C. Secure lid.

Water Parameters pH 6.5–8.5, temperature 22–28°C. Adaptable to wide hardness range. Slightly hard, neutral water is ideal. Weekly 25–30% water changes maintain health and color quality.

Feeding Omnivorous. High-quality flake food, micro pellets, frozen brine shrimp, daphnia, and color-enhancing foods with astaxanthin or spirulina. Varied, high-quality nutrition is particularly important for maintaining the intense metallic blue coloration. Feed two to three times daily.

Sex Ratio and Male Display Keep 1 male to 2–3 females. Males display intensely to females — groups produce constant color displays. Ensure sufficient females to prevent over-harassment.

Reproduction Prolific livebearer. Females produce 20–60 fry every 4–6 weeks. Dense planting allows fry survival. Separate fry for intentional rearing.

Color Maintenance Metallic blue coloration can fade in old, heavily inbred lines. Source from quality breeders who refresh their lines regularly. Feed color-enhancing foods and maintain optimal water conditions.

Health Notes Hardy and adaptable. Monitor for velvet and internal parasites in new stock. Quarantine all new fish. Maintain clean, well-oxygenated water.

Long-term Notes Moscow Blue Guppies maintain their metallic coloration best when fed color-enhancing diets and kept in clear, well-oxygenated water. Aging males sometimes show fading of the metallic sheen — this can often be reversed partially through improved nutrition and water quality. Maintaining a high-quality broodstock line through selective breeding extends the color quality to subsequent generations. The deep metallic blue of the Moscow Blue Guppy is best appreciated in aquariums with full-spectrum or daylight-type LED lighting, which renders iridophore-based coloration most accurately and vividly. Using a dark background and dark substrate creates the maximum contrast for displaying the Moscow Blue's metallic coloration to greatest visual effect throughout the display tank.