Ranavirus

Ranavirus is a group of viruses that cause sudden, often fatal disease in amphibians (and reptiles and fish), spreading rapidly and sometimes wiping out whole ponds or collections.

Like chytrid, it is a strong reason to quarantine new animals, never mix wild and captive animals, and never release pets. Signs can include sudden death, bleeding, or skin ulcers — an emergency for an exotics vet, not something to treat at home.