Cardinal tetras dying

[Scrumpy]

I fishless cycled my tank so I could put a full load of fish in. So far so good except for the cardinal tetras. My ammonia and nitrites are 0 ppm and nitrates < 30 ppm. pH is 8.2 from the water board report, and it's hard to tell what the best colour match is on the tank water but I think 7.8-8.0 ish. The water is naturally hard, (I'll dig out the water board report if you need an actual figure) but I boiled a lot of it before I put it in and I have a huge piece of bog wood which I hope will slightly soften the water.
I handled the fish as gently as possible, floating the bag while adding scoops of water to acclimatise them to temp and pH.
Anyway, in 3 days, 4 of my 8 cardinals have died. They appeared healthy, but in hours one by one they developed pale patches on their bodies, started hiding away from the school and then dropped dead in front of me. A fish can go from swimming about happily, to dead in a few of hours.
I've searched the disease databases but the closest thing in appearance is neon disease except that only one had a patch on his dorsal fin and neon disease seems quite slow. These fish go from healthy to dead in hours.
Please can anyone tell me what is wrong, and how to save the rest of my fish?
Many thanks

 

[ronrca]

My first guess would be high ph and my second, climatization. I have heard of this many, many times. I introduced my cardinals not by using a bag and at certain intervals adding water. This method for some reason does not work very well for cardinals and most people whos cardinals were dying used this method.

I use the "drip method", the same I use for discus. I put the cardinals with the water they came in into a pail, perferably a 5G pail. Then using a airtube hose, I start siphoning water from my tank into the pail. I also attach some air valves (the same as controlling air flow) inline and slow the water down to little more than a drip. I then leave the water siphon into the pail until it is 75% or more filled. It usually takes me around 3 hours but so far seems the best way to climatize cardinals. My 11 cardinals are doing great since I introduced them 4 months ago.

 

[eseow]

I agree with "Ronrca". This method is best for delicate fish. Cardinals are usually recommended also for 6 month or older established tanks also. The slow acclimation process can be extended for longer time if needed. As for my local fish wholesaler, Discus are acclimated in same bag & shipping box fore 2 weeks, before transfer to tanks. This is not an unusual thing to do for delicate fish. Hope you have good luck with Cardinals. *crazysmiley*

 

[Scrumpy]

Thank you for the advice...I'll wait a while before I get any replacement fish  then, and try yout drip method.
Another fish died this morning...would acclimatation account for continued deaths? If it was climatisation wouldn't the shock kill them quicker and not be still killing them 4 days later? Just wondering
BTW, the cardinal page on this site suggests my pH is ok?

I had no idea this would all be so stressful! I'm spending hours peering at my fish wondering if their breathing looks laboured, if they're behaving oddly, are their scales less irridescent, is that eye looking funny, is their poo supposed to be red? OMG LOL

 

[Scrumpy]

Risked it and got some more cardinals. Dripped water into the bucket over 4 hours until it was full. When i tipped the fish into the tank they'd gone white! :-@ I was ceratin they'd all die, but not one has. All coloured up quickly overnight and now fattening up and looking healthy. Thanks for the advice

 

[capncrunch5177]

Another suggestion is to check the ph where you bought your cardinals.

I only have neon tetras and thankfully I found out the first store I was considering has a ph of 7.2 and my tank is between 7.4-7.6. I don't know if they would've survive, but I bought from a closer store (so the source of water would be the same) which had a ph in the same range.

I also agree that ph of 8 and above is a bit high for cardinal tetras, at least from all the sources I'm hearing..