Check adult requirements
Record the baseline and check variety, adult size and horizontal space. Do not infer the aquarium's condition from a single sign. Confirm scientific identity, adult size, diet, social behaviour and swimming zone.
Then compare heavy waste production and oxygen demand 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 social needs, substrate and maintainable filtration before continuing. Keep a reference so the result can be compared. Plan the complete group and monitor feeding, breathing, injury, shelter and space use.
A bowl cannot provide suitable volume, exchange or swimming length for a goldfish.