Check adult requirements
Record the baseline and check the actual thermal range of each species. Do not infer the aquarium's condition from a single sign. Confirm scientific identity, adult size, diet, social behaviour and swimming zone.
Then compare seasonal heating or cooling requirements with livestock needs and recent changes. Look for genuine overlap in water, flow, territory and feeding throughout the year.
Assess compatibility and welfare
Adjust one variable and assess a community compatible throughout the year before continuing. Keep a reference so the result can be compared. Plan the complete group and monitor feeding, breathing, injury, shelter and space use.
Coldwater does not mean every unheated room temperature is suitable.