The debate over releasing fish into the wild is not really a debate. It is illegal, enough said. Now if you want to get into the fine points of the matter. Most of the time nothing will happen, but it can and does all the time. Invasive species will be eaten; infected species will die and not cause wide infection. Now let’s look at disasters (if you call such a common event that), which happen with many invasive species (which is all a novel disease is).
Go to Africa. Expose yourself to Ebola Zaire. Do you come home to your family? That is your original location after all (just like returning fish). It is the same. The scenario could be smallpox and Indians or any other of many scenarios. When a species gets exposed to a new disease the results are catastrophic.
You are from your home. You get put in a new “tank” (i.e. African rainforest / aquarium) and pick up novel disease. Return home and expose original population (native aquatic system / your family), effects are devastating. It does not matter that you are from there or really the time of exposure. I can not make it simpler that. If you can not understand that scenario, then you are lacking in basic biology and pathology knowledge. Also if you keep any tropical’s you are doubling down on the risk.