When guppies lose colour or develop stress shading, people often blame genetics or assume the fish is permanently “less nice” than the photo. In reality, guppy colour is strongly influenced by environment. Stress, unstable water, temperature swings, and social pressure can all dull colour quickly. The good news is that in many cases, colour returns once conditions improve.
Common causes of dull colour
- Water instability: ammonia/nitrite, high nitrate, or frequent swings.
- Temperature stress: too cold slows metabolism; too hot reduces oxygen.
- Diet gaps: inconsistent feeding or low-quality staples.
- Bullying: fish under pressure show less colour and hide more.
- Lighting mismatch: harsh lighting can wash out colour and increase hiding.
How to bring colour back
- Stabilise water: consistent water changes and clean feeding.
- Improve oxygen: especially important in summer.
- Feed for consistency: quality staple plus occasional high-value treats.
- Reduce stress: add cover and fix chasing dynamics.
How long does it take?
Some improvements show within days (behaviour and fin posture). Colour often takes a couple of weeks to fully rebound as fish settle and feed consistently. Young males may also “finish” colour as they mature, so patience matters.
Dull colour is usually a message: something about the environment is stressing the fish. When you address the cause, guppies often reward you by colouring up far beyond what you expected.
