Start with the enclosure
Check the basics for Omothymus violaceopes: fresh water, suitable moisture, a secure retreat, good ventilation and a practical temperature range of 23–28°C. A clear husbandry problem matters more than a single evening of unusual activity.
For Singapore Blue Tarantulas, use moisture-dependent setup with deep lower substrate, good ventilation and a constant water source. If the enclosure is obviously too wet, too dry or difficult for the spider to use normally, correct that issue before looking for a more complicated explanation.
Know what is normal
For Omothymus violaceopes, Singapore Blue Tarantulas are arboreal tarantulas, so normal retreat use should make sense for that lifestyle. A hidden spider is not automatically a stressed spider, and a visible one is not automatically comfortable.
With Omothymus violaceopes, changes from the individual's usual routine are more informative than a generic list of 'stress signs'. Compare activity, feeding and retreat use with what the same spider normally does.
Climbing, pacing and restlessness
If a Singapore Blue Tarantula repeatedly climbs or paces, check enclosure shape, moisture and recent disturbance. Mature males of Omothymus violaceopes may also roam much more after the ultimate moult.
One short burst of activity from Omothymus violaceopes matters less than a persistent pattern combined with poor body condition or an obvious enclosure problem.
Feeding changes
With Omothymus violaceopes, food refusal in Singapore Blue Tarantulas is often normal around premoult, after a heavy meal or following a rehouse. Keep water available and remove ignored live prey.
If Omothymus violaceopes stops eating but remains well hydrated and otherwise behaves normally, observation is usually more useful than repeatedly opening the enclosure and offering food.
Changes that need quicker attention
In Omothymus violaceopes, visible injury, haemolymph loss, severe dehydration, inability to stand normally or major loss of coordination in a Singapore Blue Tarantula deserves prompt attention.
If Omothymus violaceopes is physically deteriorating, correct any obvious husbandry problem immediately and seek experienced or veterinary help where appropriate.