I keep goldfish in large outdoor pots (homemade ponds). Other than noting their swiftness when surfacing for food, it is difficult to determine if my goldfish are unwell. It is only obvious they are sick when they start to float sideways; they usually die soon after. I would like to be able to recognize sickness before they get to such a critical stage.
Is it a sign of good health when goldfish rise quickly and gobble up the food?
Are there other signs to indicate if my fish are healthy (or sick)?