* Look for signs of aggression. If one goldfish is nipping at another, chasing it, or trying to dominate it, this is a sign that they may not be compatible.
* Observe their body language. If the goldfish are swimming together peacefully and not showing any signs of aggression, this is a good sign. However, if one goldfish is hiding or staying away from the others, this could be a sign that they are being bullied.
* Check for injuries. If one goldfish has any injuries, such as torn fins or scales, this could be a sign that they have been attacked by another goldfish.
* Consider the size of the tank. If the tank is too small, the goldfish may not have enough space to swim around freely and may become stressed, leading to aggression.
If you are concerned that your goldfish are not getting along with each other, there are a few things you can do to help them:
* Increase the size of the tank. This will give the goldfish more space to swim and reduce stress levels.
* Add plants and decorations to the tank. This will provide hiding places for the goldfish and help to break up the line of sight, reducing the likelihood of aggression.
* Feed the goldfish regularly and in small amounts. This will help to keep them from getting hungry and aggressive.
* Monitor the goldfish closely and remove any that are showing signs of aggression. This will help to prevent the aggressive goldfish from harming the others.
By following these tips, you can help your goldfish live together peacefully and happily.