Why do fish stop swimming?
One common cause is improper water temperature. If your fish’s water is too hot or too cold, they will be very inactive. Check your heater and verify that your aquarium is at the right level. Other possible causes are overfeeding and improper water quality.
Should fish be constantly swimming?
Most fish need to keep moving even when they’re sleeping, so that they keep a constant flow of water moving past their gills to maintain a proper oxygen level in their bodies. For some larger fish, like sharks, this can take the form of swimming at a slower rate when sleeping.
Do fish stop swimming to sleep?
Where a fish sleeps depends on the fish species. Coral reef fish may float in place and simply stop moving when they want to sleep. Nurse sharks may rest along the sea bottom or near a rocky cave. Some fish do more to protect themselves while they rest.