Sorry to hear about the loss. Butterflies are sensitive fish. I know it’s a pain but anyone that does QT can tell you it makes things more enjoyable in the long run and less expensive. It gives the fish a chance to build up strength even if they seem fine there’s a lot of ailments you can’t see at first. You can also make sure they are eating which is much harder for them to do when they don’t have an established territory. I would seriously consider starting a QT. You can get lucky, a lot of people do. I kept reef tanks for about ten years before I started QTing but ever since I started I won’t ever add a single thing to my tank; fish, inverts, coral, rock, algae, anything that goes in my tank gets QT’d. That’s just my preference though. I know a lot of guys that don’t. I just got to a point of getting sick of loosing fish and also wanted to try some of the harder to keep fish and with certain fish you really don’t have a choice if you want to be successful.
But regardless of if you choose to QT or not I would definitely switch up the methods used to acclimate. I always test the salinity of the bag before adding a fish. I don’t necessarily use a specific time limit. I go until the salinity is the same by using drip method (time varies between 30 min to 2hrs). I also add methylene blue and an air stone to the acclimation container. Especially if they were shipped. (Be sure to remove water as the container fills and add fresh SW back to the display otherwise your ATO will top off with fresh RODI and dilute the tank). The methylene blue will give them a good boost, helps get oxygen back into their blood, and has a bunch of other beneficial properties. Then I put the fish in bag and float to temp (don’t add water from bag to DT). This will give you a chance to see how the other fish will react with the new guy.
Do you have pics of the fish that have died? In the tank and after death? Some of the guys on here are really good at determining cause of death.
