Fu's are extremely sensitive to copper, while I suggest never getting a lion from sources running copper, this is a death sentence for a fu. Healthy lions are very resistant to protozoan diseases, they have a special cuticle layer and even shed their skin, which makes it very difficult for a protozoan to attach. A healthy lion kept in an observation for a month will be a very unlikely suspect to transport a protozoan disease to your dt. The only meds I recommend for lions is in regard of internal parasites; prazi pro, general cure, seachem metro, and fritz paraguard I consider safe, There is a strong argument that prophylactic copper treatment is more harmful than good for any fish.