Clamped fins
Fins held tight against the body.
Fins folded flat against the body instead of spread, often with slow swimming or hiding. It is a sign of stress or illness, not a disease of its own.
- Do this first
- Test the water and check the temperature against the species' range.
- Call a vet when
- If fins stay clamped for several days in good water, or other signs appear, ask a fish vet.
Likely causes
- Poor water quality
- Water too cold for the species
- Bullying by tankmates
- The start of an infection or parasites
What to do today
- Test the water and check the temperature against the species' range.
- Change 30 percent of the water if anything is off.
- Watch the tank for chasing; separate a bully.
When to call a vet
If fins stay clamped for several days in good water, or other signs appear, ask a fish vet. A vet who treats fish can examine it and prescribe treatment; your local fish store or aquarium society can often recommend one.
Stop it happening again
Keep each species in its temperature range and with peaceful tankmates. How to set up a quarantine tank.
Sources: Merck Veterinary Manual: Management of aquarium fish; Merck Veterinary Manual: Disorders and diseases of fish; UF/IFAS: Ammonia in Aquatic Systems.