Any biology folks out there?

[tazdvl]

OK this post might seem confrontational, but I hope it isn't considered hostile. I have read many times the matching salinity when introducing new fish into new tank is important. But could someone please point me in the direction what this number might be. I find it hard to believe that a .001 to .003 would be hard for a marine life to overcome. Seems like there would be massive die-offs over reefs after a large rain. I sort of understand the osmotic pressure on cell walls from high school biology class. Is there any authoritative source I can go to to see this information backed up with studies?

[CHSUB]

Seems like there would be massive die-offs over reefs after a large rain.

that would be one large rain storm!!!!

[Sk8r]

Well, you're actually right: fish can move when they need to, so they don't linger where it 'tastes' wrong, but IME a .002 difference is not a bad jump. As long as you're that close, fine.

OTOH, I don't recommend acclimation, which has killed a lot of fish through too long an acclimation (and ammonia, which starts a process when a shipping bag is open.) The better procedure is to check with your shipper as to what salinity it keeps x specimen, then pre-set your qt tank to that salinity. Just float the bag for 15 minutes to equalize temperature, then check bag salinity to be sure you were told the truth, and if the fish's bag water is within .002 of your qt water, put him right on into qt with no dipping and dripping at all. Adjust the qt over time to match the dt just by evaporation.

[mets17127]

I have a bio degree, but never learned about this stuff til after I got in the hobby. Basically, look at it like another stressor to an already super stressed fish. Yes, you probably won't pop his swim bladder with a .003 difference, but stress can and does kill fish. I match salinity as best as possible when I introduce a new fish to my qt, and know that one LFS keeps salinity really low. Basically, I err on the side of a lower salinity qt, as I've read that going from high to low is fine. That way, I can raise the qt to match the DT over the course of the qt period

[Reef Frog]

.001 or .002 differences aren't a problem. But most people keep a reef tank at 1.026 salinity and many on line sellers and local fish retailers keep their salinity at 1.017 and even lower. That's a BIG difference and trial & error and practical experience have shown that it is too much of a difference to overcome in a half hour of drip acclimation. And with drip you can have ammonia & temperature issues as already mentioned. That's why it is recommended.

Since we're best off putting a new fish in quarantine anyway, setting that water salinity to what the shipper has kept our fish in for a long while is extremely simple and the logical thing to do. There just is no down side to doing it this way.

[snorvich]

.001 or .002 differences aren't a problem. But most people keep a reef tank at 1.026 salinity and many on line sellers and local fish retailers keep their salinity at 1.017 and even lower. That's a BIG difference and trial & error and practical experience have shown that it is too much of a difference to overcome in a half hour of drip acclimation. And with drip you can have ammonia & temperature issues as already mentioned. That's why it is recommended.

Since we're best off putting a new fish in quarantine anyway, setting that water salinity to what the shipper has kept our fish in for a long while is extremely simple and the logical thing to do. There just is no down side to doing it this way.

This.