Shy Rosy Barb

Question
I have 3 rosy barbs in my 10 gallon tank. One of them became very shy lately. He is hiding out all day in a cave and only comes out to eat. All 3 fish are males and they don't bully him. The tank is properly cycled. No Ammonia, Nitrite or Nitrate levels and the PH is 6.8
He does not look sick. Why is he acting like this?

Answer
While it may not appear to you that the shy one is being bullied, in fact, he is. Especially considering there are only males. While barbs can be kept together, sometimes they single out a weaker or more shy fish and bully him. The most common beginning signs are hiding. Take a good look at the fish, is he losing his color or are his fins slightly torn looking? The fact that he is hiding says that he is not comfortable with being with the other two barbs. Also, make sure the shy fish does not have a disease or parasite as this can cause him to hide as he knows the other fish will try to eliminate him if he is sick. He may not be showing outside signs yet but he may be in the beginning stages, just keep a close eye on him. If the problem is bullies there is not much you can do about that but to either remove the shy fish to another tank or remove the bullies to another tank. If he develops a disease or parasite you will need to treat. In the best of circumstances it would be good to remove him to treat him in another tank but if this is not possible you can treat him in the tank he is in now. Just observe and watch all of them closely to narrow down what it is. I hope this helps. Let me know if you need anything else.