None actually until you can diagnosie the sickness. Unless you have symptons, mediciating will only increase the stress factor. Medicating for not apparent reason will do more harm than good. The best 'medicine' is a clean tank, clean water. Getting new fish, use a quarintine tank, raise the temp to 90F, treat with salt and feed them excellant quality food with lots of vitamins. Dont forget aeration also! *thumbsupsmiley*