Bumblebee Goby

[penguinexdeus]

I had two bumblebee gobys (brackish) that I got online.  They came in fresh water so I quarantined them in fresh water.  Used the med trio preventatively and also added stress guard. They were eating baby brine, thought everything was good.  After a week of the preventative med trio I did a 50% water change.  A day or two later I notice one was looking a little fuzzy and the other was showing signs of starting.  I used Kanaplex and the next day (yesterday) the fuzz on the one seemed to have gotten worse to the point it was having trouble swimming.  Woke up this morning to find both dead.

Any thoughts or suggestions on what the fuzz is/was?  Sorry i don't have any photos of it in tank, but here's a photo of them out of tank.  The fuzz stuff is built up and i couldn't get any off with a tooth pick.  Looking to figure out what it was an how to treat it in future.   Parameters after taking them out of tank tested as Ammonia - 0.25,  Nitrite - 0, Nitrate - 20, ph - 7.8, gH - 10, kH - 6

[Cory]

Likely it was a fungus. Salt can fight it off, fish are under a lot of stress when in the incorrect salinity and very susceptible to disease. likely when you changed out the meds, it let nothing to prevent it from growing again.