Saltcorner
By Bob Goemans
By Bob Goemans
Dear Bob,
I have a 4' x 18''x12'' marine aquarium up and running for about 4 months. It uses an Undergravel Filter. - Yes, I know they are out of favour! Using powerheads and a large External Filter. Stocking is 1 Clown Wrasse, 1 Twin Spot Wrasse, 1 Velvet Damsel, 4 Green Chromis, and one each of a cleaner, blood, and dancing Shrimp. The tank also has various clams, a sea urchin, and some mushroom and toadstool corals. All are doing very well and have been for many weeks. I then thought I would move up a bit in price, as everything was happy and of course water checks were fine.
Ammonia NIL, Nitrite Nil, Nitrate 10 (Same as my tap water), Calcium 440 and pH 8.4.
Then came the problems..............
As each new fish was introduced (taking an hour to acclimate), the same pattern happened.
Day 1 - Bit of displaying with Wrasse ..... but nothing serious.
Day 2 - Seemed very happy and browsing/eating well.
Day 3 - Lethargic, hiding a lot not eating.
Day 4 - DEAD
I have now lost 1 Yellow Tang, followed by another Yellow Tang. Followed by a rusty Angel and most recently a beautiful Bi-Colour Angel. All went through exactly the same pattern.
HELP, my Bank Manager will be getting cross and I want to get some more fish before he forecloses on me!
David Lippiett, England
Dear David,
Thanks for your letter. Assuming your water quality is as good as you say, and there was little or no stress induced by the wrasses, and no obvious signs of maladies present in the new fish, I would think the cause was "salinity induced stress." If there was more than .003 unit's difference between your dealers tanks and yours, i.e., the dealers may have been 1.021 and yours was 1.025, the induced osmotic stress can cause the death of these fish, just as you mention. Fish can be immediately placed in much lower salinity conditions, however, must not be immediately placed in a salinity that is more than .002 - .003 units higher. If your dealer has a salinity that is more than .002 - .003 units lower than your aquarium, you must place your fish in a holding tank of the same salinity as your dealers tank and carefully raise it no more than .002 - .003 units per 24 hours. An hour does not suffice.
Hope this resolves the mystery.
Cheers,
Bob Goemans
