I quote Okguy!

"The tank is 1 1/2 old now"

If this is months not years. This could be the potential problem.
Kevin

Do you just put them in or do you acclimatize first?

ok. The tank is 30 gallons. Currently has 1 occelaris, 1 diamond goby.
about 20lbs of live rock. it has a shallow sand bed. Mostly because I didn't buy enough sand. It's about 1 inch thick.
No corals at he moment, there is also a remora skimmer.
Temp is 76F.
To acclimate the fish to the tank, I float the bag in the tank for about 20 mins to adjust the temperature then add water to the bag and float for about 15 for mins then add the fish to the tank.

AFter I added him he was stayed in plain view in one area of the tank and even ate some food later that night.

I saw him again swimming in the open the next day then I went away for 3 days and came back.
He was again swimming around fine.
Yesterday proceeded to hide then he died.

Ammonia - 0
nitrites - 0
nitrates -5
salinity - 1.027 - usually lower than that.
there isn't algae but there is detrius in the tank.

I want to add another koralia to the tank but ther is a good amount of flow.
I have fake corals in the tank at the moment since I dont' have any real ones. They are on the bottom of the tank and they move in the current.

The tank has been set up for about 1 1/2 years.

asherah

Your params dont seem too bad...

It might be that the water from your LFS is quite different from your own & you need to acclimatise more slowly.

For example, putting a small amount of tank water at a time into the bag & then floating for 10 mins before adding a bit more & repeating this step until the water in the bag has been 'equalised' to the water in your tank.

Have you checked the parameters of the water in the bag?

For various reasons, sometimes a LFS might keep a lower salinity in their fish tanks than we do in our reefs - say as low as 1.017.

In this case it can take some time to properly acclimatise the new fish.

.

ARE you dumping LFS water into your tank when you add new fish? Some stores add copper to their water.

i have also heard of stores getting fihs in water at salenity as low as 1.005

no I don't add the lfs water to my tank. I'm going to hagv to find out what the salinity is at the store.

asherah

Got some hermits and a shrimp the other day from BA's, salinity was 1.030 with refractometer.

whoa!
and I thought mine was high.

asherah

Fish unfortunately do... JUST die.