Why is my sucker fish lying on its back?

There are a few possible reasons why your sucker fish might be lying on its back:

1. Water quality issues: Poor water quality, such as high levels of ammonia or nitrite, can cause sucker fish to become stressed and lethargic, leading them to lie on their backs. Check the water parameters of your aquarium and make sure they are within the ideal range for sucker fish.

2. Inadequate oxygen levels: Sucker fish require a lot of oxygen to breathe, and low oxygen levels in the water can cause them to become distressed and swim abnormally. Ensure that your aquarium has adequate water flow and aeration to maintain sufficient oxygen levels.

3. Illness or injury: Sucker fish can be susceptible to various illnesses and injuries, which can cause them to lose their balance and lie on their backs. Look for any signs of illness or injury, such as discoloration, bloating, or open wounds. If you suspect that your sucker fish is sick or injured, consult with a veterinarian or an experienced aquarist.

4. Old age: As sucker fish age, they can become weak and lethargic, which can lead them to lie on their backs. If your sucker fish is old, provide it with extra care and attention, and be prepared for any age-related health issues.

5. Stress: Sucker fish can be stressed by various factors, such as overcrowding, sudden changes in water temperature, or the introduction of new fish into the aquarium. Stress can cause sucker fish to behave abnormally, including lying on their backs. Try to minimize stress factors in your aquarium to help your sucker fish thrive.