Fish communicate through behavior and appearance, and changes are usually responding to something in their environment. This section covers the questions aquarium owners ask when something doesn't look right — from hiding to surface-gasping to not eating — with the water chemistry context that makes everything else make sense.
A fish floating sideways or upside down is almost always a swim bladder problem — here are all 8 causes and exactly what to do about it.
A betta sitting motionless on a leaf can mean nothing at all — or it can be cold water, swim bladder disorder, or illness. Here's how to tell the difference.
A fish refusing food can be something simple — wrong food type, acclimation period — or a sign of illness or poor water quality. Here's how to tell.
Fish gasping at the surface is almost always an oxygen or water quality problem. It's a distress signal that needs prompt attention.
Previously active fish that suddenly disappear behind rocks or plants are usually responding to something. Water quality, temperature, and aggression are the top three things to check.