Can you put an 18 month old guinea pig with 6 week that are both females?

It is generally not advisable to put an 18-month-old guinea pig with 6-week-old guinea pigs, even if they are both female. Here are a few reasons why:

1. Size difference: 18-month-old guinea pigs are typically much larger and heavier than 6-week-old guinea pigs. This can lead to the younger guinea pigs being injured or bullied.

2. Developmental differences: 6-week-old guinea pigs are still developing their social and behavioral skills, while 18-month-old guinea pigs are fully mature. This can lead to misunderstandings and conflicts between the two age groups.

3. Health risks: 18-month-old guinea pigs may be more likely to carry diseases or infections than 6-week-old guinea pigs. This can pose a health risk to the younger animals.

4. Stress: Introducing a new guinea pig into a group of established guinea pigs can be stressful for all involved. This stress can lead to health problems, weight loss, and conflict.

For these reasons, it is generally best to keep guinea pigs of different age groups separate. If you want to introduce new guinea pigs to your group, it is best to do so slowly and gradually, and to keep a close eye on them for signs of stress or conflict.