bleeding

Hello my flame tetra got a red spot under it's mouth and started swimming strange and bumping into things what can that be? it happened very fast and are my other tetras in trouble as well? Please help. Check all water parameters and they are all good.

Hi there I got a few more guppies for my tank the other day, one is yellow but he appears to have a blood red mark on the top of him from his nose to top fin it's quite big like a oval shape coming 1/3 down his side on both sides he seems happy enough eating fine and swimming fine is it blood or...

My BN has a red patch on his/her belly and also red skin on half of his/her body. I heard this could be a sign of Internal bleeding, stress and if he/she is ready to breed. Please help! What should I do?