Japan Blue Guppy

An electric, metallic blue sheen, most often along the lower body, rear body and base of the tail. It is often paired with sword tails. Males show this best. Females are larger, plumper and mostly silver-grey, with some tail colour in fancy lines.

It is a colour strain of the Guppy, not a separate species, and it appears in many lines. Breeders use strain names loosely, so photos and breeder descriptions are the best guide.

Males are more colourful, with elongated fins and a gonopodium, which is a modified anal fin used for mating. Females are larger, plumper and duller.

Provide dense plants or floating cover, to give females a break from males and to protect fry. Keep the flow gentle, because long tails make swimming harder. Guard filter intakes, so that fry are not pulled in.

Very peaceful and active. Males display to females constantly and can pester them if there are too few females.

Keep in a group, with at least two or three females for every male. A single-sex group of males also works if you want to avoid fry.

Not territorial. Males compete for females, but this rarely causes injury.

Suits quiet tanks with platies, corydoras and small peaceful fish that like similar water. Long fins attract nippers, so avoid fin nippers, and avoid bettas, which may attack long-tailed males. Adults may eat shrimplets. Guppies from different lines will interbreed, which matters if you want to keep a strain true.

Hard, alkaline water suits guppies best. Fancy strains are usually happiest at about 22 to 26 °C.

An omnivore that eats small invertebrates, algae and plant matter, and readily takes prepared foods.

Feed small amounts, because guppies overeat readily. Crush the food for mixed groups with fry.

A livebearer that breeds readily with no special setup. Gestation takes 4 to 6 weeks, and females store sperm, so a female can have several broods from one mating. Provide dense plants or a separate tank, because adults eat their young. To keep a strain true, keep it apart from other guppies, and avoid heavy inbreeding, which can weaken the fish.