if i get two new hermit crabs that lived in a tank from outside can those two crabs bring gnats to my cage?

Yes.

I suggest you isolate the new crabs in a different tank until you're sure they don't have gnats.

oh great! :) thx! and one of the new ones looks like hes about to change his shell! funn. :D

If you introduce hermit crabs that have been living in a tank from outside, there is a possibility that they could bring gnats into your cage. Gnats are small flying insects that are attracted to moist environments or decaying organic matter, and they can sometimes be found in outdoor tanks or enclosures. Here's how you can address this issue:

1. Quarantine the new hermit crabs: Before introducing them to your existing cage or tank, it is important to isolate the newly acquired hermit crabs in a separate enclosure. This will help you monitor them for any signs of pests or diseases.
2. Inspect the new hermit crabs: Carefully examine the new hermit crabs for any signs of gnats or other pests. Look for tiny flying insects around their bodies, shells, or in the tank they came from.
3. Clean and sanitize the tank: Thoroughly clean and sanitize the tank or enclosure that the new hermit crabs were living in. This will help eliminate any potential gnat larvae, eggs, or other pests that may be present.
4. Create a suitable habitat: Ensure that the habitat for your hermit crabs is clean, well-maintained, and properly set up. This includes using clean substrate, providing fresh water and food, and maintaining appropriate humidity levels.
5. Monitor the enclosure: Keep an eye on your hermit crab enclosure for any signs of gnats. If you notice any small flying insects, take immediate action to prevent them from multiplying. This may include removing any decaying organic matter, such as fruit or uneaten food, and implementing solutions to control or eliminate the gnats, such as using fly traps or sprays.

By following these steps, you can minimize the risk of introducing gnats or other pests into your hermit crab enclosure. Remember that regular maintenance and cleanliness are essential in providing a healthy environment for your hermit crabs.