Betta fish lying at the bottom of the tank may be caused by factors such as abnormal water temperature, poor water quality, disease infection, environmental stress, or aging. It is necessary to identify the cause based on specific symptoms and take targeted measures. The detailed analysis is as follows:
Abnormal Water Temperature
Low Water Temperature: The suitable water temperature range for betta fish is 20-30°C, with 24-27°C being the most ideal. If the water temperature drops below 20°C, the betta's metabolism will be affected, leading to reduced vitality and the phenomenon of lying motionless at the bottom of the tank.
Large Water Temperature Fluctuations: Betta fish are quite sensitive to water temperature changes. If the water temperature suddenly rises or drops, the betta may lie at the bottom of the tank due to inability to adapt.
Solutions:
Use a heater to maintain a stable water temperature, ensuring it stays within the suitable range.
Avoid frequent water changes or changing a large amount of water at one time to reduce water temperature fluctuations.
Poor Water Quality
Excessive Ammonia Nitrogen and Nitrite: When the concentrations of ammonia nitrogen and nitrite in the water exceed safe levels, they can damage the betta's gill tissue, causing rapid breathing, abnormal secretion of body surface mucus, and eventually leading the fish to lie motionless at the bottom of the tank.
Unsuitable pH Level: Betta fish thrive in neutral water, with a suitable pH range of 6.5-7.5. If the water is too acidic or too alkaline, it will also affect the betta's health.
Turbid Water: If the filtration system is inadequate or water changes are not performed in a timely manner, the water may become turbid, affecting the betta's breathing and activity.
Solutions:
Regularly test the water quality to ensure the concentrations of harmful substances such as ammonia nitrogen and nitrite are within safe limits.
Use water conditioners or regulators to adjust the pH level of the water.
Change the water regularly to keep it clear.
Clean or replace the filtration system to ensure effective filtration.
Disease Infection
Bacterial Infection: Symptoms such as white film on the body, fin rot, or red spots may indicate a bacterial infection.
Parasitic Infection: Infections by parasites such as Dactylogyrus or Gyrodactylus can also cause betta fish to lie at the bottom of the tank.
Fungal Infection: The presence of cotton-like mycelium on wounds may be a sign of fungal infection.
Solutions:
Observe the betta's physical condition. If abnormal symptoms are present, isolate the fish for treatment promptly.
Use appropriate medications for treatment, such as methylene blue, formalin solution, or malachite green.
Set up a medical isolation tank equipped with a sponge filter and Indian almond leaves to provide a good therapeutic environment for the sick fish.
Environmental Stress
Mirror Reflection: Betta fish have an aggressive nature. If there is a mirror reflection on the tank wall, it may continuously trigger the betta's fighting instinct, leading to exhaustion and causing it to lie at the bottom of the tank.
Tank Location: If the tank is placed in an area with frequent human movement or is exposed to other noise disturbances, it may affect the betta's rest and activity.
Tank Mates: Keeping betta fish with other fish species may cause them stress due to fighting or competition.
Solutions:
Attach dark-colored wallpaper to the tank walls to reduce mirror reflections.
Place the tank in a quiet area with minimal human traffic.
Avoid keeping betta fish with other fish, or choose gentle-tempered fish species for cohabitation if necessary.
Other Factors
Aging: Betta fish over 3 years old may naturally have reduced activity levels and tend to lie at the bottom of the tank.
Environmental Monotony: Although betta fish are easy to care for, they still need a certain amount of environmental stimulation. If the betta is the only fish in the tank, it may lack energy due to loneliness.
Solutions:
For aging betta fish, lower the water level to 12-15 cm to facilitate breathing, and increase the water temperature to 28-30°C to promote metabolism.
Add aquatic plants, small decorations, or floating plants to the tank to provide a comfortable environment and some environmental stimulation for the betta.