Here are some possible reasons why one gerbil might be getting fatter than the other:
* Diet: One gerbil might be eating more than the other. Check their food intake and ensure they're both eating a balanced diet of gerbil food, fresh vegetables, and occasional treats.
* Activity Level: The less active gerbil might be gaining weight due to lack of exercise. Ensure they have a large cage with plenty of space to run, tunnels, and toys for play.
* Underlying Medical Condition: There could be an underlying health issue like a thyroid condition or hormonal imbalance that is causing weight gain.
* Age: Older gerbils may become less active and prone to weight gain.
Here's what you should do:
* Schedule a vet appointment: A veterinarian can perform a physical exam, assess their weight, and run any necessary tests to determine the cause of the weight gain.
* Observe their behavior: Pay attention to any changes in their behavior, such as decreased activity, lethargy, or changes in appetite.
* Keep a food journal: Track what they eat and how much.
* Maintain a clean environment: Ensure their cage is clean and has fresh water available at all times.
Don't hesitate to seek professional help for your gerbil's health. A veterinarian can provide the best advice and treatment for your furry friend.