Salt Levels

[mbu man]

can this be right i bought a fish at weekend and i tested the water to see the salinity of it, it was very low only just touching 26?
but a while ago when i bought some fish from the same plasce it was very high at 34??
how comes their is such a difference, even thiugh it is the same shop??

 

[AK77]

Hi Mbuman,

Its possible that your LFS runs hyposalinity in (some at least) of their tanks. The fish you purchased may have come from the quarantine tank and the fish had been in there sufficiently long enough, so as to be free from parasites. The other fish may have come from post quarantine tanks or tanks that share their water supply with corals/invertebrates. This would explain the higher (normal) SG levels.

Hyposalinity is a common thing in the aquatics trade, as it can reduce the stress on a fish apparently and also means that disease/parasites are largely void from the fish.

 

[Musho3210]

i wouldnt say it reduces stress.... maybe not cause too much but it does kill many parasites through osmotic shock.

 

[AK77]

i wouldnt say it reduces stress.... maybe not cause too much but it does kill many parasites through osmotic shock.

I could have sworn I read that it reduced the "load"/"stress" on the fishes liver or one of the other internal organs with regard to expelling toxins or something of that nature.

 

[Musho3210]

hmm, i wouldnt not believe it and it is probably true, but overall i wouldnt think it would reduce overall stress, what good is your liver when your heart is beating two times faster than normal lol (example, not saying that hypo salinity raises pulse rate....)

But i could be wrong...

 

[andywg]

i wouldnt say it reduces stress.... maybe not cause too much but it does kill many parasites through osmotic shock.

I could have sworn I read that it reduced the "load"/"stress" on the fishes liver or one of the other internal organs with regard to expelling toxins or something of that nature.

A fish has to work constantly to maintain its salt levels lower than the surrounding area through osmoregulation. It was thus reasoned by some that lowering the salinity would lower the stress on the fish's ability to osmoregulate. However, the fish generally have evolved over millions of years to be in their natural water, so placing them into hyposaline conditions may well have trouble. It's similar to on of the arguments for using salt in FW tanks.

In moderate amounts (down to 50% sea water) there appear to be no problems, and most fish only start to suffer short term problems when the SG of the water is below 1.007.

 

[AK77]

Thank you Andy! I knew I had read something somewhere and is why I put "apparently" in my post as I was unsure to the scientific validity of it lol.

Is it just a myth or is there concrete evidence to support it??

 

[andywg]

It is somewhat of a myth. Many fish can survive long term at reduced salinity, but you are keeping them in water they have not evolved for. It certainly doesn't seem to do a huge amount of damage in the short term, but I doubt whether it truly helps.

 

[mbu man]

right. thanx
so what would be the perfect salinity for a tank that has fish and anemones??
i was told by my lfs that they prefer more of a higher salinity of 32 to 36, mine is 32.

 

[AK77]

Anywhere between 1.024 and 1.028. Mines becoming a reef tank with the addition of corals now, so I keep mine at 1.026 which is about 34. 32 will be fine.

 

[Musho3210]

mines at 1.027, NSW varies at around the levels ak said, i would keep it at 1.026 since it leaves room for evaporation and top off. Also 1.026 is what most dealers keep coral tanks at (many dealers keep fish in hypo-salinity which is very low salinity)

I just forgot to top off for a while, and then did a water change and forgot to add RO water etc, so that rose my salinity, i want to lower it but.... I dunno, just havent gotten around to doing it,.