PlanetCatfish.com

Hi. I want to give you a little background first and then you will have the whole picture and may better be able to help me.
I ordered four Sterba's and two twin tail Betta's from a reputable online aquaria store and received them on Tuesday (they were shipped on Monday at 7:30 PM and arrived Tuesday at 4:00 PM). I followed the adjustment procedure completely. After almost two hours of acclimating I released them into the aquarium (I'm using spring water in the tank, my tap water is uncontrolable). The tank had been set up for three days. Heat is at 78 to 82. Upon release two of the Sterba's were dead and two were doing okay. I added the two that were okay and one of the twin tail betta's to the tank. The next day everyone seemed to be doing okay. I added my other cory cats (Bronze and Spotted) to the tank. The next day one Sterba was dead and two spotted were dead. The day after that another spotted died and today two spotted are dying. Do Cory Cats die of stress? I had to change out the water and substrate because I used gravel and the food had clouded up the tank horribly (I cleaned and changed the water on the third day). They now have white sand, plants and structures to hide in and behind (this set up has been running since Friday). The temp is holding steady at 80 to 82, all of the freshwater tests are normal (pH - 7.6, Ammonia - 0, Nitrite - 0 and Nitrate - 0). I did apparently mess up in one respect because I added salt, I thought it would help them be less stressed. I didn't do my research and that part is my fault. I'm used to just having Oscar's and Betta's and they tolerate salt.
SO, basically I'm sure I made a lot of mistakes. I should have done more research.
Do you think that the Cory's died of stress, salt, stupidity or what? I don't want to lose the remainder ( I have seven left - 1 Sterba, 3 Bronze and 3 Spotted and the Betta). Please help, I will do whatever it takes.
Thanks, Bridge

Salt is definitely not good for the Corydoras species, but I doubt that a moderate amount of salt would be immediately lethal to them.

I'm a little bit worried that your nitrate value is zero - this should be reading some number above zero. It's an indication that the tank isn't matured - in which case you probably have some occurance of nitrite and ammonia. This MAY have been the cause of death.

Obviously, the weren't in perfect order when they arrived, so the stress of shipping is certainly a factor in the puzzle, although that certainly shouldn't have killed your OTHER fish (where did they come from?) are pretty hardy, and I guess your spotted ones are [1], which are another hardy species - although both species prefer slightly lower temperatures.

[1]There are however dozens of spotted cories, so they could be something else...

--
Mats

There's a posting somewhere here about Cories releasing stress hormones. When these hormones aren't released prior to being bagged, they can release the hormone in the bag. Did I imagine this posting? This is an obscure question to ask, but did you take the temperature of the water the Cories came in? If the weather was cold/freezing, even with the heating pads in the box, they could have gotten cold. It may have been quite a temperature fluctuation from the time they left the shipper to the time they got to you. It could have been as much as a 15 degree rise in temperature in 2 hours. Stress could have been a large factor here. Have you called the company to tell them what happened?
Amanda

The Sterbai I ordered from a highly respected online aquaria store and the Spotted and Bronze Cory's I bought at Pet*mart. The Bronze Cory's must be really hardy, I have not lost any of them and they act crazy all of the time. After a water change last night they all seem to be doing well. I will receive my replacement Sterbai next week (for the two that were dead upon arrival and the one that died a day later). How should I adjust them to the tank? The other Cory's are already in my quarntine tank. I'm keeping an eye on the levels. Thanks again for your help.

If you check the temperature of the arriving bag before you put it into the tank, you will find out if they are MUCH cooler than the tank [more than around 10'F], you will want to acclimatise them to the warmer water slowly. One way to do that would be to float the bag inside bowl or something with water that is halfway between the bag and the tank temp, or bag temp +10'F, whichever is lower. Let the bag sit there for about half an hour, then check the bag temp and bowl temp. If the temp is not the same as the bowl, then you need to wait longer.

Once the bowl and bag temp are the same, take the difference of the bag and tank, if it's still more than 10'F, repeat the bag-in-bowl procedure.

Once the diff is less than 10'F, you should be OK to go through the normal acclimatisation process: float bag for 15-20 minutes, then start adding tank-water to the bag, a little bit at a time, waiting a few minutes between each bit of water - start with a small amount of water, and as the bag fills up you can use a bigger amount. This will allow the fish to get used to the water in your tank. You should almost fill the bag with tank-water, and then release the fish into the tank. It's best to release fish with the lights off, and let them swim out of the bag by themselves (rather than turning the bag upside down and dumping them in the tank...)

--
Mats

ozrockhound,
You may find these links helpful.
Amanda