Fish Dying, what am I missing? Please help!

[EMazurk]

I have had 36 gallon FOWLR tank that has been set up for almost 3 months. I started with 2 clown fish, a blue-green chromis and 2 turbo snails. After carefully monitoring the parameters and seeing everyone was doing well, I added a royal gramma and 3 hermit crabs. After about 2-3 weeks, it seemed like the royal gramma and the blue green chromis died over night. One day they were swimming around eating, the next they are barely swimming, on their side, and then dead. I immediately took a water sample to my LFS who found everything was normal (ammonia - 0, nitrite - 0, nitrate - 10ppm, phosphates - 0, pH 8.2). The only thing that came back off was salinity, hadn't realized my refractometer needed to be recalibrated, the water was at about 1.029. I slowly lowered the tank to 1.025 and no other fish/inverts were lost.
After about 2 weeks making sure things were good, I added a fire fish and diamond goby. All fish were happy, normal, the over night the fire fish is dead at the bottom. 2 days later, one of the hermit crabs has now died.

I retested everything, and it's all still normal, including salinity. I really feel awful for these guys, but at the same time am doing everything what I think is right. Weekly 10% water changes, feeding twice daily making sure they're all getting some, etc.

Can anyone help me figure out what I might be missing that is causing sudden fish loss literally over night?

 

[mcgyvr]

clown fish bullies

 

[EMazurk]

I have not seen the clownfish bully any other fish. I watch pretty often during the day and they all swim around pretty peacefully. I also don't see any signs of nipping on the deceased. The fire fish literally was just laying at the bottom dead in perfect shape aside from the whole breathing thing.

 

[etazeta956]

Dealing with a very similar situation now, just posted a thread. Mine (I think) is an extra aggressive Coral Beauty. I just removed him and will revamp from here. I noticed he wouldn't really "bully" as much as make quick darts at the others, forcing them into the rocks. Then they wouldn't come out to eat. Then dead. Good luck and keep us posted.

 

[EMazurk]

Thanks for the input and sorry you're having a similar problem. I don't think it's an issue of bullying, the fact that I just lost a hermit crab wouldn't make sense, the clowns never interact with them. Even the fire fish which is timid was always out swimming around and eating. I'd suspect it would have spent most time in the rocks if it was being bullied. Instead it was happy one second, lifeless on the sandbed the next.

I just wish I knew what else to test for, when the water parameters are all perfect and organisms are dying, it's perplexing and frustrating.