Guppy

Water parameters

Tolerated range for this species. Aim for the middle of each band rather than the extremes.

Tank and habitat

Substrate: any.

Behavior

Plant interaction: plant safe.

Feeding

Omnivore that eats anything: flake food, micro pellets, frozen bloodworm, frozen brine shrimp, frozen daphnia, blanched peas, blanched zucchini, algae, biofilm. Not picky, not slow, always hungry. Feed twice daily in small amounts. Color-enhancing food with spirulina, astaxanthin, or carotenoids improves the vibrancy of red, orange, and yellow coloring in males. Newly born fry eat crushed flake and baby brine shrimp from day one. Overfeeding is easy because guppies always act hungry; restrain the impulse.

Compatibility

• The classic beginner livebearer. Peaceful, colorful, and breeds in any container of water that's vaguely tropical. The challenge isn't keeping guppies alive; it's preventing population explosion.
• Males have long, flowing fins that attract fin-nippers. Avoid housing with tiger barbs, serpae tetras, and other known nippers. Even mildly nippy species target guppy tails because the waving display fins trigger a chasing response.
• Keep in a ratio of 2-3 females per male. A single female with multiple males gets harassed constantly and will die from stress. An all-male tank avoids breeding but some males redirect aggression toward each other's fins.
• Hybridizes with endler's livebearers (Poecilia wingei) because they're closely related or possibly the same species. If keeping both, house them separately or accept that offspring will be hybrids.

Origin and habitat

Poecilia reticulata is a small livebearer native to northern South America and the southern Lesser Antilles, including Venezuela, Trinidad, Barbados, the Guianas, and northern Brazil. Wilhelm Peters described it in 1859. The common name comes from Robert John Lechmere Guppy, a Trinidad-based naturalist who sent specimens to London, after which Gunther named a synonym, Girardinus guppii, in his honour in 1866. Guppies have been released around the world, often deliberately for mosquito control, but reviews found that effort made little to no measurable dent in mosquito numbers while doing harm, or at best nothing, to native fish. Part of what makes them such successful colonisers is the female's ability to store sperm for months and produce several broods from one mating, so a single pregnant female can seed a whole population. Wild guppies are small and drab; the veiltail, delta, snakeskin, Moscow, and other fancy strains, with their vivid colour and long fins, are all products of selective breeding. Females are noticeably larger than males, the species averaging only a few centimetres.

Breeding

Guppies breed on their own with no help from the keeper. The male's anal fin is modified into a gonopodium that delivers sperm internally, and the female stores it to fertilise several successive broods. Gestation runs about three to four weeks, after which she drops a brood of live, free-swimming fry, on the order of twenty to forty in a typical female and more in large ones. The fry are functional from birth and eat crushed flake and baby brine shrimp at once. In a community tank the adults, the mother included, eat most of the fry, so dense floating cover or a separate tank is needed to raise many. Breeding guppies for particular colours and tail shapes is a hobby in its own right, and the underlying colour genetics, a mix of sex-linked and autosomal genes, is intricate and hard to predict.

Common problems

The biggest practical issue is the fragility of mass-produced fancy strains. Decades of intensive inbreeding on fish farms have left many chain-store fancy guppies weak, and keepers often see new fish die off one by one over the first few weeks, a mix of that built-in fragility, transport stress, and the jump between store and home water. Buying from a local breeder rather than a chain greatly improves survival, and wild-type or endler-cross guppies are far tougher than fancy strains if hardiness matters more than looks. Day to day, the common ailments are columnaris and other bacterial infections that erode fins, internal parasites that cause wasting, and swim-bladder trouble. Males' long tails are the usual casualty of fin rot, so steady water quality is the main defence.

Bioload

Further reading

• Setting up a breeding tank