Help! I have a sick Yellow Watchman

[sharper]

I am completely new to this marine tank stuff. I have a 12 gallon Nano that has completely cycled and we got our first fish, Yellow Watchman Goby. We've had him for a week and he'd been doing great. He was eating, he found a cave to call home, he was healthy all around.
A couple of days ago, we got a pulsing xenia frag and a couple of green mushroom frags for our first corals. My husband put both corals in the tank with rubber band on the xenia and super glue gel on the green mushrooms.
Last night, I go to feed the goby and he doesn't come out to eat. We look really close to see he's hiding deep within the rocks. He pokes his head out for a second and he was holding his mouth open. To get a closer look, we netted him up and held the net close to the glass to see him. His mouth looks swollen. He closes it sometimes, but mostly hangs it open, and it seemed to be kind of white. And it seems like there's a dark spot halfway down his body.
This morning, we look and he's swimming all over the tank with was very unusual. Instead of crawling on the floor, he's swimming all over the place and will take a rest up on top of the rocks. His face is really turning white, but the dark spot seems to be fading.
Can anyone tell me what's going on?! I'd really like to save this guy. He's the only fish in the tank and we love him!
Thanks!

 

[sharper]

thanks for the help

thanks for the help

Well, I waited a long time for any help from any marine forums and no one responded. I got off of work at noon today, and my Goby was already dead when I got home. He was all white, his eyes were cloudy and his face was swollen.
Please someone let me know what this was so that I can make sure I get my aquarium treated and to be more prepared in the future.
We are devastated at our loss.

 

[Sk8r]

It was probably a fungus infection---different than a bacterial infection but sometimes entailing bacterial after the fungus has had a go. When people get something of the same, it's usually in the mouth, or on the foot [athlete's foot] and it requires a treatment other than antibiotic. It's usually a case of a short qt. So sorry nobody was online who could help...
First step, I'd avoid that fish source: yellow watchmen are very hardy fish, and usually don't get diseases. If you have to go online, I recommend Foster/Smith---they've been a good source for me. I've never had a sick fish from them.
Second, check your params: you're a nano, and your water quality is critical and delicate.
Look up: body velvet, mouth velvet. You might want to stock one broad-spectrum antibiotic: Maracyn, I think is good; one antifungal dip [it's been 3 decades since I had an outbreak, so I can't remember: I'm sure they've got a better treatment now]; and if you get ich, just go hyposaline.
To set up a qt tank, get a cheap plastic box and keep flow high and lighting minimal, with spot-on heating. No sand, no decor, the one place you can use a regular airpump and floss filter.
To catch a difficult fish: lower your water level in your nano temporarily: it won't hurt your corals if you're fast. The fish will go to the low spot, and you can net him and pump the water back in fairly quickly.
To set up a qt, borrow water from your tank, and add about 20% new water. The bacteria in the water will quickly colonize the floss.
Never medicate your main tank, even if the preparation says 'reef safe.'

 

[sharper]

Thank you so much! I'm printing out your post for future reference. And we will definately make sure we have these items on hand just incase.

Do you think we should wait for a period of time to get a new fish?

 

[sharper]

Hey, just to give an update. We took our water up to the LFS to get it tested to compare to our tests. They said that our Salinity was at 1.029, which is odd because our hydrometer at home reads 1.022.
So we can't figure out why that is other than our hydrometer is broken. I think we will buy a new one tomorrow.
We got some new water and had it half fresh and half salt. We were instructed to change out a gallon a day till it reads normal. Our PH was a little low, but we knew that.
They guy at the LFS said that with a salinity that high could of easily killed off our goby because of the gravity.
I hope our water gets normal again soon.