I have an oscar (around 6in) in a 40 gal tank. I recently re did the aqua scape from gravel to sand and plastic hide to wood. I also picked up a bichir (around 6") they lived together not so good at first but don't care about each other anymore. I added a BGK aswell. I know I have iver crowding problems but that's beside the point. My oscar and bichir for the first time yesterday at 1130pm on nov 6th started to attempt a tank escape and charged are the hlass and anything else. I did an immediate water change and all seemed good. Today I had reduced eating. They ate half their usual portions. And the oscar seems to be laying on his side now and the bichir still swimming erativly. My mom noticed a small white worm she said looked like the blood worms I feed the the BGK but I never saw anything. Based on a quick google search it might be possible for a parasite but I'm not sure. I poked the oscar and he is swimming now as of 1015pm on nov 7th. Any advice or idea for me would be greatly appreciated. This tank has been running no problem for about 7 months now. Thx.