What disease could cause a tropical fish to have a hole in its head?

Answer by  JRossi17 (788)

The disease is called HLLE, it is caused by a deficiency in vitamins, usually vitamin c. To treat this you have to quartine the fish and fix all leaves to the proper adjustment.

Answer by  peters (296)

If there is any discoloration associated with the hole, it is probably a fungus. If there is not, and it is a clean round hole then it is very possible your fish has worms. In both cases there are treatments you can put in the water to treat what is wrong.