Temperature is one of the biggest levers in guppy care. It affects metabolism, appetite, oxygen demand, breeding speed, and lifespan. Many Australian homes experience seasonal swings, and those swings can show up as changes in behaviour and colour. The goal isn’t to lock your tank to one “perfect” number, but to keep temperature stable and understand what happens when it runs warmer or cooler.
The guppy sweet spot
Most guppies do well around 24–26°C when water is stable and oxygen is good. At this range, fish eat well, colour up nicely, and breeding is consistent.
What happens when you go warmer
- metabolism increases (fish eat more, waste increases)
- oxygen availability decreases (risk of fast breathing)
- stress risk rises during heat waves
What happens when you go cooler
- appetite drops and growth slows
- breeding slows (fewer fry, longer gaps)
- fish may look “less active” even if healthy
Stability is the main goal
Rapid changes are more stressful than being slightly warm or slightly cool. Sudden swings can trigger clamped fins, flashing, or general stress. Use a reliable heater, keep the tank away from direct sun, and increase aeration when summer temps climb.
Once you treat temperature as a stability factor — not a single magic number — your guppies will be more consistent in colour, behaviour, and health through the year.
