I have a normal BP who is about 9 years old that I have had for 3 years. He is showing some signs that are making me think that he could have a respiratory infection. On the other hand, it is only one sign and everything is pretty much normal. About once every 1-2 hours, I hear a loud "hiss-ish" sound coming from him. It sounds like it could be wheezing or other noise that could signal an RI. He is also moving around his tank a little more than normal. He has been making these noises for months, but they are somewhat more frequent in the past few weeks. I have checked inside his mouth and there is mucus coming out of his mouth or nose. He is also eating normally. I don't want to take him to a vet if he doesn't have an RI. Could someone tell me what these symptoms mean?