It is all about the amount of risk you are willing to take. If your DT is filled with loads of expensive, healthy fish, adding a non-quarantined royal gramma is a really bad idea.
Quarantine, properly done, eliminates the majority of communicable pathogens (say 95%). It also screen for about 75% of the losses in the new fish themselves.
Here is our current process:
2024 Quarantine Procedures Jay Hemdal David Scarborough Protozoans (Cryptocaryon/ich, Amyloodinium/velvet) and Metazoan trematodes/flukes are by far the most common parasites found on newly acquired fish. A carefully managed, proactive quarantine process can effectively eliminate these...
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Jay