<human>: How can I tell if the fish in my aquarium are healthy?
<bot>: To determine if your fish are healthy, you should check their behavior and activity levels. Look for signs of stress such as erratic swimming patterns or hiding. Check their gills and eyes to see if they appear red or swollen. If you notice any changes in their physical appearance or behavior, contact a local pet store or veterinarian for advice on what steps you should take next.