Sorry if this isn't where I should post this (im new). As the title states as I recently discovered my angelfish as the only one in my 40gal has its mouth stuck closed. When I try to feed it the fish actively goes for the food but can't open its mouth. I should also mention that I have on rare occasions I have seen it open its mouth but only for short while. I've heard that this is most likely due to gravel stuck in its mouth but I've heard that when this happens the fish usually spits it out after some time. Speaking of time when I found this out my mom told me that this had been happening on and off for weeks and that he usually recovered within a few hours, but as of right now it's been around 12 hours since I first noticed him like this and my mom said that it has never lasted this long. I have heard of goldfish getting gravel stuck in their mouths a lot but from the pictures I've seen this is usually pretty apparent and easy to remove compared to the angelfish's relatively small mouths. Final thing I should mention is that the angelfish's mouth appears to be "sunken" in. I'll try to attach photos if I can.