Blue Grass Guppy Care Guide - Tank Setup, Diet & Breeding

Blue Grass Guppies are a fancy guppy strain recognised for the blue-green, grass-like patterning that often covers the body and tail. Selective breeding can produce considerable variation, with some fish showing vivid blue tails, dark reticulation and contrasting body colours. Their flowing fins are especially prominent in males.

Like other guppies, they are lively, curious and constantly on the move, spending much of their time in the middle and upper areas of the aquarium. They are generally peaceful, though males may repeatedly court females and compete with one another for attention.

The wild guppy is naturally found in a wide range of shallow freshwater habitats, including streams, pools, drainage channels and quiet margins of rivers. Populations are adaptable and may encounter clear, flowing water as well as warm, vegetated habitats with changing conditions.

Blue Grass Guppies have been developed through generations of selective breeding in the aquarium trade. Their striking appearance and engaging behaviour have made them one of the most popular ornamental livebearers, although selectively bred strains can be less robust than wild-type guppies if breeding focuses too narrowly on appearance.

Blue Grass Guppies are a selectively bred colour variety of Poecilia reticulata rather than a separate wild species. The guppy originates from northern South America and nearby islands, including Venezuela, Guyana, Suriname, French Guiana, Trinidad and Barbados.

A group of Blue Grass Guppies should have an aquarium of at least 40 litres, with a footprint around 60 × 30 cm or larger; a bigger tank is preferable for a mixed-sex group or a growing population. Use gentle filtration with secure flow, open swimming space and plenty of live plants, including fine-leaved species or floating cover for fry. A dark, fine-grained substrate can enhance their colours, while smooth decorations and unobstructed areas help protect their delicate fins.

Males usually reach about 3–4 cm (1.2–1.6 in), while females may grow to around 5–6 cm (2.0–2.4 in). Females are noticeably larger and heavier-bodied than males.

Blue Grass Guppies are omnivores and do best on a varied diet of quality small flakes or micro-pellets supplemented with frozen or live foods such as brine shrimp, daphnia and mosquito larvae. They also graze on soft algae and naturally occurring microorganisms. Feed appropriately sized portions and include some vegetable matter, such as spirulina-based food, to support balanced nutrition and colour.

Blue Grass Guppies are peaceful community fish and can be kept with other calm, similarly sized species such as platies, mollies, swordtails, peaceful tetras, rasboras, white cloud mountain minnows and small Corydoras. Avoid fin-nipping species such as tiger barbs, aggressive or predatory fish, and tankmates large enough to eat them. Long-finned males may be particularly vulnerable to fin damage, and mixed-sex groups can produce many offspring quickly.

Blue Grass Guppies are livebearers that breed readily in a mature aquarium. After internal fertilisation, the female typically gives birth to around 20–60 free-swimming fry after approximately 21–30 days, although brood size varies with her age and size. Provide dense plants or a breeding refuge for the young, as adults may eat fry. Females can store sperm and produce several broods from a single mating, so separate sexes if population control is important.

Males are smaller and more colourful, with enlarged flowing tails and a pointed anal fin modified into a gonopodium. Females are larger and less vividly marked, with a rounded abdomen and a fan-shaped anal fin; a dark gravid spot may be visible near the rear of the abdomen when carrying developing young.