Size and growth
Adult Poecilotheria formosa reach about 15–18 cm (6–7 in) and are fast growers. Adult Poecilotheria subfusca reach about 14–17 cm (5.5–6.75 in) and are moderate growers. That affects how quickly Salem Ornamentals and Ivory Ornamentals move through sling and juvenile enclosure sizes.
Do not use size alone to estimate age in either Poecilotheria formosa or Poecilotheria subfusca. Sex, feeding and individual variation can change the pace of growth even when two spiders began at a similar size.
Enclosure and lifestyle
Salem Ornamentals are arboreal, while Ivory Ornamentals are arboreal. Build the Poecilotheria formosa enclosure for an arboreal spider and the Poecilotheria subfusca enclosure for an arboreal spider instead of assuming two tarantulas need the same shape of setup.
For Poecilotheria formosa, substrate depth, retreat position and usable space should match its arboreal lifestyle. Apply the same rule separately to Poecilotheria subfusca; the enclosure should make normal behaviour easy rather than forcing either species into a generic layout.
Temperature, water and moisture
A practical temperature range for Poecilotheria formosa is 22–27°C; for Poecilotheria subfusca, it is 19–24°C. Stable room conditions are more useful for both species than chasing small fluctuations within those ranges.
For Poecilotheria formosa, maintain moderate moisture, strong ventilation and a water dish. For Poecilotheria subfusca, maintain moderate moisture with excellent ventilation; avoid warm stagnant conditions. In both enclosures, keep fresh water available and adjust substrate moisture to how quickly the setup actually dries.
Temperament and maintenance
Poecilotheria formosa is an Old World species, while Poecilotheria subfusca is an Old World species. That background is useful when planning maintenance, but individual Salem Ornamentals and Ivory Ornamentals can still differ noticeably in speed and defensiveness.
With both Poecilotheria formosa and Poecilotheria subfusca, locate the spider before opening the enclosure, use long tools when they make the job safer and keep a catch cup ready for rehousing. Handling is not required for routine care.
Male and female lifespan
Male Poecilotheria formosa generally live roughly 3–5 years, while females can live 10–12 years. Male Poecilotheria subfusca generally live roughly 3–5 years, while females can live 10–12+ years.
Those lifespan ranges make sex particularly relevant when comparing Poecilotheria formosa with Poecilotheria subfusca. A confirmed female of either species is normally a much longer commitment than a mature male, and the exact age of an older juvenile may be impossible to know.
UK availability and trade notes
In the UK hobby, Poecilotheria formosa is currently classed as uncommon, while Poecilotheria subfusca is classed as rare. Stock changes between specialist sellers, captive-produced batches and show weekends, so availability should be checked at the time of purchase.
For records and purchases, use the scientific names Poecilotheria formosa and Poecilotheria subfusca as the main identifiers. Current trade notes list Poecilotheria formosa as 'CITES Appendix II; UK Annex B' and Poecilotheria subfusca as 'CITES Appendix II; UK Annex B', so check current requirements before any international movement where controls may apply.
Practical difference in day-to-day care
The practical difference between Poecilotheria formosa and Poecilotheria subfusca comes from the combination of lifestyle, adult size, growth and moisture needs. Those factors change how much substrate, vertical space and maintenance access each enclosure needs.
Whichever species you keep, let the individual spider settle into an enclosure designed for its own biology. That applies equally to Poecilotheria formosa and Poecilotheria subfusca: fresh water, secure housing and patient observation matter more than trying to make the two species behave the same way.