When guppy fins look “spiky” or held tight, people often assume it’s fin rot. Sometimes it is damage. Often it’s clamping — a stress response where fish hold fins close to the body. These two issues can look similar at a glance, but the fixes are different. Clamping is about environment and stress. Damage is about healing conditions and preventing further tearing.
How to tell clamping from damage
- Clamping: fins are held tight but edges may look intact; fish often looks stressed or shy.
- Damage: edges are frayed or missing pieces; fin may look torn unevenly.
- Behaviour clue: clamping often comes with hiding, reduced appetite, or rapid breathing.
Common causes of clamping
- ammonia/nitrite above 0 (even small)
- temperature swings or overheating
- bullying or constant chasing
- post-shipping stress
Common causes of fin damage
- fin nipping from tank mates
- snagging on rough decor
- strong flow that drags fins into objects
Fix approach
- Test water first: remove stressors before any treatment.
- Stabilise routine: moderate water changes, stable temperature, good aeration.
- Prevent repeats: remove nippers and fin-snags.
When you get the diagnosis right, fins often improve quickly. Clamping resolves with stability. Damage heals when the environment is calm, clean, and safe from further tearing. Either way, the foundation is the same: stable water and reduced stress.
