Late last night our Retropinnis bichir began to behave very strangely. I have found some reports of other bichirs behaving similarly while searching online, but no real answers or suggestions to help the guy. He is floating tail up and spinning around the aquarium. He will settle down and lay and rest every once in a while, but then will return to spinning and rolling and laying with his belly up, or swimming upside down. There is no fungus or any external problems that I can see. Please help! We have been bringing him to the surface for air in a net periodically but even then all he does is flip around but stay mostly belly up. Water parameters are normal and all other fish are behaving normally. Thank you!