Would low salinity kill a fish?

[9supratt4]

So as many of you are aware...I lost my 2 1/2 year old naso tang today. The only thing I can figure out so far is that the tank had evaporated more water than usual. Would that kill a fish?

I didn't get to test the SG on the tank before it topped off....but just a thought.

 

[MadReefer]

Evaporation would not cause low salinity as salt doesn't evaporate. The salinity would be higher in this case not lower.

 

[9supratt4]

I'm sorry....my brain isn't working right now...don't even feel like working today. Correct...higher. Would higher SG kill a fish??

 

[MadReefer]

I would think that depends on how high.

Edit: I would think a few points up will not be a problem especially if done rather slow through evaporation. If it was very quick and real high could be a possibility.

 

[bmoney]

I had a tank that went up 1.035 and saw no problems with the fish or corals. I would think much higher then that and you would be getting into Dead Sea terroatory. The second thought I have, is if there are other fish or coral's in the tank do they seem affected. If it was high enough to kill one there would be others affected maybe not kill them, but they would show some sign of a problem.

 

[Hawkeye]

A friend of mine had a miscalibrated refractometer and every time he changed the water, he diluted the tank. Basically it was a brackish water tank - (FO already) and killed half of the fish he had including the supposedly indestructible blue devil damsel (he had 3). Surprisingly the clownfish and sailfin tang survived.

I would think that evap should NOT cause the fish to succumb unless it already had some kind of depressed immune system, and the additional stress of the salinity caused it to go over.

I'm sorry to hear the loss. naso tangs are one of my favorite.

 

[NikkiT]

I generally agree with Phil. Small gradual changes in SG that over time add up to large changes won't usually kill a fish. That said, it all depends on what level the SG of water got to. It comes down to the fish's ability to osmoregulate. The higher the SG, the more a fish has to work to stay hydrated.