Betta fish lying at the bottom of the tank may be caused by low water temperature, poor water quality, disease infection, environmental stress, or improper feeding. Targeted measures should be taken based on specific symptoms. Below is a detailed analysis and corresponding solutions:
1. Low Water Temperature
Cause: Betta fish are tropical fish, and their optimal water temperature range is 25-28°C (77-82.4°F). When the water temperature is too low, their activity decreases, leading to lying motionless at the bottom of the tank.
Solutions:
Use a heater or heating mat to adjust the water temperature, maintaining it around 28°C (82.4°F) for a period of time to kill water mold in the water.
If low water temperature is detected, immediately replace part of the water with new, warmer water. However, ensure the temperature difference between the new and old water does not exceed 2°C (3.6°F) to avoid stressing the betta.
2. Poor Water Quality
Cause: Water quality is a critical factor affecting betta health. Poor water quality—such as excessive ammonia/nitrite levels or drastic pH fluctuations—can cause discomfort in bettas, leading them to lie at the tank bottom.
Solutions:
Change water regularly to keep it clean. It is recommended to replace 1/3 of the tank water weekly, using a "small and frequent" water change method to avoid sudden osmotic pressure changes from large one-time water changes.
Use tap water that has been exposed to air (for chlorine removal) or purified water to raise bettas. New water should be aerated for at least 24 hours in advance, or a water conditioner can be added to neutralize chloramines.
Regularly test water parameters using tools like the API Freshwater Test Kit to ensure harmful substances (such as ammonia and nitrite) are within safe concentration ranges.
3. Disease Infection
Cause: Betta fish may lie at the tank bottom due to diseases like bacterial infections, parasitic infestations, or fungal infections. These diseases are usually accompanied by symptoms such as white film on the body, fin rot, red spots, or cotton-like mycelium.
Solutions:
Observe the betta’s physical condition. If abnormal symptoms (e.g., white film on the body, fin rot) are found, immediately isolate the sick fish for treatment.
Use appropriate medications based on the type of disease. For example:
For bacterial infections: Use a methylene blue bath.
For parasitic infestations: Use a short-term formalin solution bath.
For fungal infections: Treat with malachite green.
Maintain clean water quality during treatment and avoid frequent water changes, which may worsen the condition.
4. Environmental Stress
Cause: Betta fish may experience stress from environmental changes, such as transport stress or stress from adapting to a new environment. These stress responses can cause them to lie motionless at the tank bottom.
Solutions:
For transport stress: Immediately replace 1/3 of the water after the betta arrives home, adjust the water temperature to 26-28°C (78.8-82.4°F), and add 1 Indian almond leaf (a natural anti-stress tool) to help the betta relieve stress.
For new environment adaptation stress: Lower the water level to a height where the betta can easily access the water surface, and add 1 Indian almond leaf to create a secure environment for the fish to recover. Additionally, place the tank in a dark area to allow the betta to regain its condition on its own.
5. Improper Feeding
Cause: If bettas do not receive enough food, they may feel hungry and weak, leading them to lie at the tank bottom. Additionally, overfeeding or feeding inappropriate food can cause gastrointestinal discomfort in bettas, resulting in the same behavior.
Solutions:
Feed appropriately and ensure the correct food is selected. Choose betta-specific food or high-protein, high-quality floating food to feed the bettas.
Soak the fish food in warm water before feeding, and feed an amount roughly the size of a grain of rice each time to avoid gastrointestinal discomfort from overfeeding.
Establish a "fasting day": Stop feeding the betta on 1 fixed day per week to allow its gastrointestinal system to rest and recover.