Most my fish died!

[blaxsun]

Fish are shipped overnight in small bags without lack of oxygen, there has to happen a lot before a big tank runs out of oxygen. A couple of hours without power won't do it. A bigger problem in this case is a temperature drop.

When fish are shipped the bags are inflated and filled with pure O2 from a cylinder, so you really can't draw any comparison.

 

[Idech]

I’m new at this, curious where you were going with this comment…. Could vacuum the substrate lead to bad things like fish deaths?

When you have a deep sand bed, you either vacuum regularly or you don’t. After a while, there will be bubbles of anaerobic bacteria living in the sand, and if you disturb them, they will die and it will cause an ammonia spike.

This spike will be taken care of by the live rock and biological media in a few minutes but while it’s happening, it can kill fish. I’ve lost a dozen fish that way. I vacuumed a deep sand bed six months after I set it up.

Mind you it was in freshwater, but I doubt it’s any different in saltwater. That’s why I brought it up.

 

[Jay Hemdal]

I have no idea lol

How does velvet happen and how do you treat that?

Amyloodinium/velvet is a protozoan infection that causes rapid breathing and then death within 72 hours or so if untreated. You may or may not see spots on the fish, if you do, they will be like a fine dust. The fish may hover in the water flow before dying. It is unusual for it to just show up in a tank without having added some animal recently that could have transferred it to the tank.

Supersaturation is tricky to diagnose, that's why I asked about the fish's mouths, and if you saw silver air bubbles in their fins. If an air leak develops on the suction side of a pump, like when a sump catches air, nitrogen gas can become supersaturated to the point of killing the fish. Then, the leak can stop on its own, or you fill the sump up.

The surviving goby is the confounding factor - velvet should have taken it out. I have had bottom dwelling fish survive a supersaturation event by hiding under rocks, where the partial pressure of the gas is apparently less.

Jay

 

[jmichaelh7]

Did you find out what caused it

 

[Harold999]

When fish are shipped the bags are inflated and filled with pure O2 from a cylinder, so you really can't draw any comparison.

Without constant surface movement gas exchange is very limited to none.

 

[blaxsun]

Without constant surface movement gas exchange is very limited to none.

While I do agree, we're only theorizing that an extended power outage was the cause. I've had velvet and it will kill absolutely everything if treatment is not initiated immediately, so the sole surviving fish and length of time that's passed make this less likely.