Guppies are usually confident and visible, so when one starts hiding it grabs your attention fast. Hiding is not a diagnosis by itself — it’s a stress signal. Sometimes it’s harmless (new fish settling). Other times it’s the first sign of a tank imbalance or social problem. If you check a few key things in the right order, you can usually work out what’s going on.
1) Is the fish new?
New guppies often hide for the first day or two, especially in bright tanks. Low light and calm routine usually fix this naturally.
2) Check bullying and tank dynamics
If one fish is being chased, it will hide. Watch feeding time and look for one fish being targeted. Tank mate issues are a top cause.
3) Test water (especially ammonia and nitrite)
Even low-level ammonia or nitrite can make fish clamp fins and hide. Water issues are often invisible until fish show behaviour changes.
4) Temperature and oxygen
Overheating or poor oxygen can make fish lethargic and hide near calm zones. In summer, this can appear quickly.
5) Early illness signs
If the fish hides and also refuses food, clamps fins, or breathes heavily, treat it as a health warning. Stabilise water first and then consider targeted action.
Hiding is useful information: it’s your tank telling you something is off. If you check water, temperature, and social pressure, most hiding cases become clear — and solvable.
