Sick swordtail

[Wenrl]

My blood red swordtail male has been hiding and this morning he is close enough for me to see him. He has this white area on his side and his tail may be rotting (hard to tell). What is this and what should I do? Note: he was getting picked on by another male. Could this be injury-related.

 

[libertybelle]

Bullying can be circular. Bullying can be the cause of an injury but it can also be because the fish is sick. It’s not uncommon for fish to pick on their weaker tankmates.

What other inhabitants are in the tank, how big is the tank and what are the water parameters (ammonia nitrites and nitrates at least)

Is he active or just hanging at the surface?