My tank was finally fully stocked and everything was great / everyone was active and happy for the past few weeks. Then a few days ago things started to change. I saw one fish flashing, then two, then three. The next day all the fish just seemed less active. Now they hardly move at all unless being fed. They are pretty much all flashing. I’ve checked the water params and they are perfect. I’ve been doing 20% water changes each day. Things seem to be getting worse. I don’t see anything physically wrong with the fish. No white specks. No fin rot. What’s the next step in diagnosing / treating the tank? Or is this a wait and observe situation still?
Tank: 120 gallon, with 40 gallon sump (filter sock, protein skimmer, lots of bio balls), and two canister filters, no coral, 0 ammonia, 0 nitrite, low nitrate
Inhabitants: 2 chromis, 1 dogface puffer, 1 copper banded butterfly, 4 clown fish, 1 squirrel fish, 1 lion fish, 1 snowflake eel, 1 blue tang, 1 gobby, 2 fire shrimp, 1 counch, 1 urchin
Tank: 120 gallon, with 40 gallon sump (filter sock, protein skimmer, lots of bio balls), and two canister filters, no coral, 0 ammonia, 0 nitrite, low nitrate
Inhabitants: 2 chromis, 1 dogface puffer, 1 copper banded butterfly, 4 clown fish, 1 squirrel fish, 1 lion fish, 1 snowflake eel, 1 blue tang, 1 gobby, 2 fire shrimp, 1 counch, 1 urchin