Size and growth
Adult Aphonopelma chalcodes reach about 13–15 cm and are very slow growers. Adult Aphonopelma moderatum reach about 12–14 cm (4.75–5.5 in) and are slow growers. That affects how quickly Arizona Blonde Tarantulas and Rio Grande Gold Tarantulas move through sling and juvenile enclosure sizes.
Do not use size alone to estimate age in either Aphonopelma chalcodes or Aphonopelma moderatum. Sex, feeding and individual variation can change the pace of growth even when two spiders began at a similar size.
Enclosure and lifestyle
Arizona Blonde Tarantulas are terrestrial, while Rio Grande Gold Tarantulas are terrestrial. Build the Aphonopelma chalcodes enclosure for a terrestrial spider and the Aphonopelma moderatum enclosure for a terrestrial spider instead of assuming two tarantulas need the same shape of setup.
For Aphonopelma chalcodes, substrate depth, retreat position and usable space should match its terrestrial lifestyle. Apply the same rule separately to Aphonopelma moderatum; 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 Aphonopelma chalcodes is 18–26°C; for Aphonopelma moderatum, it is 20–25°C. Stable room conditions are more useful for both species than chasing small fluctuations within those ranges.
For Aphonopelma chalcodes, keep a mostly dry setup with surface conditions with clean water available; modest moisture for smaller slings. For Aphonopelma moderatum, keep a mostly dry setup with with a water dish; avoid persistently damp substrate. In both enclosures, keep fresh water available and adjust substrate moisture to how quickly the setup actually dries.
Temperament and maintenance
Aphonopelma chalcodes is a New World species, while Aphonopelma moderatum is a New World species. That background is useful when planning maintenance, but individual Arizona Blonde Tarantulas and Rio Grande Gold Tarantulas can still differ noticeably in speed and defensiveness.
With both Aphonopelma chalcodes and Aphonopelma moderatum, 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 Aphonopelma chalcodes generally live roughly 5–8 years, while females can live 20–30+ years. Male Aphonopelma moderatum generally live roughly 4–6 years, while females can live 15–20 years.
Those lifespan ranges make sex particularly relevant when comparing Aphonopelma chalcodes with Aphonopelma moderatum. 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, Aphonopelma chalcodes is currently classed as common, while Aphonopelma moderatum is classed as uncommon. 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 Aphonopelma chalcodes and Aphonopelma moderatum as the main identifiers. Current trade notes list Aphonopelma chalcodes as 'Not listed' and Aphonopelma moderatum as 'Check current CITES rules before cross-border trade', so check current requirements before any international movement where controls may apply.
Practical difference in day-to-day care
The practical difference between Aphonopelma chalcodes and Aphonopelma moderatum 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 Aphonopelma chalcodes and Aphonopelma moderatum: fresh water, secure housing and patient observation matter more than trying to make the two species behave the same way.