Lost first fish

[HJ99]

We have a 180g DT , 250g total system. Also have a 55g set up for observation. Two weeks ago we got our first livestock. 2 clowns, 2 Bengai Cardinals, 1 Foxface, 1 lawnmower Blenny and two Skunk Shrimp. We had the fish in the 55g until Monday and decided they were fine to put in the DT. Everyone seemed much happier in the larger tank with more hiding places. Salinity 1.025. Ammonia 0, Nitrate 30, Temp 77.5. This morning one of the Cardinals is dead. No signs of disease or anything. We had noticed one of the Cardinals seemed to like getting right up to the Foxface that is about 2 thirds bigger. Could it have been stung and would it be enough to kill it ? They really are tiny. I'm getting ready to do a water change as a precaution . Thanks

 

[prdubois]

10% water change is a good idea.

 

[HJ99]

10% water change is a good idea.

What I thought. I'm heating the water in the mixing station as we speak.

 

[prdubois]

How did you move the fish from the QT? Did everything match? Could have just been stress?

 

[HJ99]

How did you move the fish from the QT? Did everything match? Could have just been stress?

Everything matched. QT is right across from DT so went from one to the other. Everybody seemed fine all week. I am thinking I may have inadvertently poisoned it with a plumbing repair. I had a drip at a threaded joint on the external return pump. The sump is in the basement. I took it apart and used a pipe sealant recommended for PVC on the joint. Fixed the leak but I'm wondering if a miniscule amount could have got into the water column. I wouldn't think it would be an issue with 250g of water but it seems like quite a coincidence. Also everything else seems fine. I posted mostly because I wondered if a Foxface sting could also be the cause or maybe just one of those things with a new fish. We are new at this and feel bad but I told my wife that we never did this before and have to expect some setbacks.

 

[Uncle99]

Maybe Bangaii taking out bangaii.
I would keep either one, or many.

 

[jeffchapok]

Have you tested for ammonia? You added quite a bioload to that tank at one time. You may have triggered a mini-cycle. Nitrifying bacteria need a chance to ramp up to handle the load.