If your betta fish is staying motionless, it could be caused by strong water flow, inappropriate water temperature, illness, environmental stress, or normal resting behavior. You’ll need to identify the cause by checking specific symptoms and tank conditions. Below is a detailed analysis of this phenomenon:
I. Water Flow Issues
Bettas are freshwater fish that prefer still water and dislike strong currents. Excessive water flow in the tank can cause them to stop swimming entirely.
Try turning off the filter and circulation system temporarily to see if the betta becomes active again. Bettas have low oxygen requirements, so shutting down these systems will have little impact on their health.
II. Water Temperature Problems
As tropical fish, bettas have specific temperature needs. Both overly low and high water temperatures can reduce their activity levels.
Low Temperature: Cold water may make bettas stop moving and even lead to symptoms similar to "cold stress." Gradually raise the water temperature to 26-28°C (79-82°F) and maintain stability.
High Temperature: Overheating can cause discomfort and reduced activity. Cool the water down or increase gentle water movement to lower the temperature.
III. Illness-Related Causes
Motionlessness can also indicate underlying health issues in bettas.
Cold Stress: Often triggered by sudden temperature changes during water changes. Affected bettas may stop swimming and show rapid breathing. Remove the betta to a separate tank for quiet recovery, raise the water temperature, and add a small amount of aquarium salt to alleviate symptoms.
Ich (White Spot Disease) or Velvet Disease: These conditions are usually caused by poor water quality or sudden water parameter changes. Infected bettas may develop white spots, fuzzy growths, or tiny parasites on their bodies, along with inactivity. Isolate the fish first, raise the tank temperature to 30°C (86°F), stop feeding for 2-3 days, and treat with methylene blue or aquarium salt baths.
IV. Environmental Stress
Bettas are sensitive to sudden changes in their environment. Events like adding new fish to the tank or changing too much water at once can trigger stress responses, leading to motionlessness.
Keep the tank environment stable—avoid abrupt changes to water quality, temperature, or lighting conditions.
V. Normal Resting Behavior
Bettas also need rest. They may stay motionless at the bottom of the tank or among aquatic plants to recharge their energy.
As long as the betta shows no other abnormal symptoms (such as physical damage or labored breathing), there’s no need for concern.