Moscow Blue Guppy

Geographic Origin and Biotope: Highly selected strain born in Moscow (Russia) during the Cold War, developed by isolated aquarists trying to fix unique color mutations starting from guppies imported decades earlier.

Taxonomy and Morphology: Moscow Blue Guppy (Poecilia reticulata). Elite poeciliid. The "Moscow" characteristic is the extension of the pigment over the entire body, including the head (a very rare trait in guppies, where color usually stops mid-trunk).

Social Behavior: Exuberant but heavy. The Moscow Blue male is often weighed down by immense dorsal fins (which fall like a cloak) and caudal fins. It swims incessantly looking for mating, tiring very quickly in case of strong currents.

Coloration and Sexual Dimorphism: Ink Blue Velvet. The male is a solid block of deep midnight blue color, almost black in some lights, metallic and sparkling under white LEDs. The female is large (6 cm / 2.4 inches), gray/silver with transparent or slightly gray/blue edged fins.

Aquarium Setup: Sweet and calm aquarium (60 cm / 24 inches). Being a prized strain, the ideal tank is a clean Iwagumi-style layout or densely planted (Dutch) with practically still water so as not to exhaust the males. Always insert floating plants to shield aggressive light.

Diet and Feeding: Exhibition omnivore. To keep the deep blue pigment (without letting it turn to red or dull yellow), administer specific feeds rich in Astaxanthin and spirulina, supplementing with live or frozen mosquito larvae (bloodworms).

Water Quality: Like all Russian and Asian guppies, it is a high-level inbred. Intolerant to soft and acidic water (the pH must be strictly above 7.2) and to nitrate accumulation. Requires regular partial changes and a GH 12-20.

Compatibility and Tankmates: Excellent prey. Their dark color and very slow swimming make them the favorite target of aggressive fish. Keep only in monospecific tanks or pair exclusively with peaceful Corydoras or Otocinclus.

Aquarium Reproduction: The Breeder's Challenge. Although they breed easily like all guppies (ovoviviparous, 30 fry a month), keeping the "Blue Moscow" line pure is very difficult. If breeders are not obsessively selected, discarding those with red or yellow spots, the strain will degrade in a few generations.

Risks and Diseases: The mutant gene and the Swim Bladder. Many high-quality Moscows develop a genetic defect in the swim bladder as they age, ending up swimming "upside down" or sinking. If you notice a zig-zag gait on the bottom, the fish is incurable.