How do you tell if fish are hungry?

Symptoms of fish stress include: * "Gasping" (rapid flapping of the gills) * Clamped fins (fins lay against the body instead of being spread out) * Loss of color * Lethargy * Not eating * Sitting on the bottom * Floating crooked If you notice any of these symptoms, check your water parameters to make sure nothing has gone wrong with the chemistry, and try changing some of the water (20-30%) to see if it improves the fish's condition.