Species identity
Fancy domestic guppies are usually Poecilia reticulata, a freshwater livebearing poeciliid. Do not treat selectively bred phenotypes as independently described species.
Aquarium targets
Practical maintenance baseline: 24–26°C (75–79°F), pH 7.0–8.2, GH about 8–20 dGH, and zero measurable ammonia or nitrite in a fully cycled, well-filtered aquarium. Keep nitrate as low as practical (often under 20–30 mg/L) rather than treating that number as a toxicological cutoff. Species tolerance is broader; stable conditions take priority.
Space and community
Plan at least 15–20 US gallons for a small breeding colony with adequate filtration, plant refuges, and room for offspring. Adult males may harass females; use social arrangements appropriate to a monitored group, or single-sex housing. Avoid automatic fish-per-gallon stocking rules.
Maintenance
Test water, feed lightly, dechlorinate replacement water and perform changes based on bioload and measured values. Salt is not a routine requirement for healthy guppy aquariums and can harm tankmates.