@VJV Some nitrifying bacteria will inevitability die off, without the presence of fish & their poop.
However, you can mitigate this by continuing to feed your corals/inverts, and also dropping in a pinch of flake or pellets every 2-3 days. But it's still a good idea to space out reintroducing your fish into the DT and monitoring ammonia while you do this; maybe add 1-2 fish per week. I recommend adding the small sissy fish ahead of the larger, more aggressive ones. ![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)