cardinal tetras

tedr108

Lifetime Charter Member
Lifetime Member
Nov 21, 2007
514
0
16
Los Angeles, CA
I recently moved 6 cardinals from my large high-tech tank to a non-CO2 tank. The cardinals started looking lethargic by day 2 and weren't too enthuiastic about eating by day 3. I moved them back to the main tank on day 3 and now they are looking healthy again -- though one of them has a spot of white fungus on his tail (will this go away now that he is feeling better?).

I checked out some of the non-CO2 tank water parameters and found 2 possible problems:

1) pH of 8.1 or so -- that's what my local tap water is
2) GH of 20 -- local tap water

I know cardinals don't like water above 7.0 pH normally, and they also like soft water. The cardinals have been doing great in my high-tech tank, I assume because 1) pH is 6.0 - 7.0 during day and night and 2) water is quite a bit softer (12 - 16GH -- are the plants and/or snails using up the calcium?). Could there be some other causes for the cardinal problem in this tank? Other fish do fine in my non-CO2 (like galaxy rasboras & panda corys).

I cut the water by 60% with RO water, so the GH is now 8.

Since it is a non-CO2 tank, I really don't mind going with all RO water and some Equilibrium to remineralize the water. I'm just hoping that remineralized RO will have a pH around 7.0 or so. I don't know much about using chemicals to reduce pH.
 

captain_bu

Prolific Poster
Nov 7, 2007
55
0
6
SF Bay Area
Did you drip acclimate them to the water in the tank you moved them to slowly? They can be sensitive to being moved. I moved a few too quickly once and lost one of them shortly afterward. This was also a situation where they were moved to a tank with a higher pH (8- 8.1).
 

tedr108

Lifetime Charter Member
Lifetime Member
Nov 21, 2007
514
0
16
Los Angeles, CA
No, I did not do that. Thanks for the reminder. I always acclimate when I bring fish home from the store, so that was dumb ... duh! :rolleyes:

I've never really monitored my tanks' water much, since all critters have been doing well -- so, I had no idea of the major differences between the 2 tanks.

Thanks again...
 

guy tillmans

Guru Class Expert
Jul 29, 2008
121
0
16
Maastricht-Netherlands
The differance in the soluted salts in the two tanks can do harm to your fish. Osmosis and diffusion. When you bring fish from a tank with lots of salts to a tank with low salts, cells of the fish will expand/swell, get hydrated. When you bring them from "low salts" to "high salts" tanks, the cells will get dehydrated. Thats why they need to get acclimatized
 

tedr108

Lifetime Charter Member
Lifetime Member
Nov 21, 2007
514
0
16
Los Angeles, CA
Well, after being moved back to the main tank, 5 of the 6 cardinals are back to normal and eating well.

1 of the 6 is eating well and doing fine, but it does have a couple of spots of white fungus. These spots are not getting bigger, but they have not shrunk in 3 days either.

First of all, is this fish contagious? Is there any chance of recovery by natural methods, or should I euthanize the little guy (if I can catch him)? I don't want to go out and buy any medicine. It's not worth it for me.