2 new clownfish died 24&48 hours :( What am I doing wrong?

[acabgd]

I'm still unsure this was an ammonia problem, but rather velvet or some other disease. Sad as any fish death would be, I think you should consider that you actually dodged the bullet by using a QT.
Imagine if you've already had $100s of fish in your tank and added the two without QT first... all would've been dead within a few days.

I think you did everything right. As some already suggested, I'd make sure to cycle the tank somewhat earlier, then ghostfeed for several days before adding fish, while at the same time making sure there is no ammonia.
I would also additionally research copper, make sure the dosing is correct and eventually hold off adding it immediately. Let the fish set in the QT for a few days then add copper.

 

[BoasNZoas]

I second the quarantine not being fully cycled. HOWEVER clowns are usually very hardy. How long did the LFS have them? Clowns are known to contract velvet, brooklynella and even uronema. The latter disease can kill very fast--less than 24 hrs.

 

[EBNewbie]

Quick update.
The LFS has offered to replace both fish. Very nice of them. I'm cycling my quarantine tank now and ghost feeding until parameters are good.

 

[mrkjeezy]

Sorry for the unfortunate deaths of your clown fish. I have no clue what could have happened. I have done tank transfer method on all fish going into my DT, none of the new tanks they were transferred to were ever cycled and have never had any problems with ammonia or fish death. I did also dose Seachem Prime daily to detoxify any ammonia in the tank. Maybe try dosing prime if you're worried about ammonia during your cycling process of your DT? Ive read many threads regarding the use of Prime during a cycle and it seems it doesn't affect the bacteria.