Banggai Cardinal - 2 of 3 Dead!

I am very new at this as this is our first salt water tank. Everything has been perfect up until now. About 2 or 3 weeks ago I bought 3 cardinals to add to my 8 month old tank. We had 2 clowns, a tiny hippo tang, and now these three cardinals which we were going to get rid of the "odd man out." The fish did fine for a while but 4 days ago one died...Not a big deal I suppose. Today a second died. Now the third looks pretty rough. He is nearly laying on the bottom of the tank unless the pumps are off for feeding. The other three look and seem as happy as can be. They are eating fine. Any ideas?? I know this is like a sin but we've never had the slightest problem and the only tests I have are for Ca and PH....also, a few days ago, I didn't have the fan on and the with the lights and the "heat wave" and being on the second floor and and no air circulation, the tank got up to like 88. Corals looked rough and it seemed as the fish were trying to jump out of the tank but I slowly lowered the temp back down to 80-82 over the next 2 days and all seemed well. Would this temp changed have killed the cardinals days later?? Thanks for your help and ASAP because I don't know if there is anything I can do but this cardinal doesn't look like he is going to make it through the night. Thanks.

 

That could easily be the cause.

Another possibility is that you don't know what your Nitrates are. If your Nitrates are extremely high, the 3 fish that you had previously have slowly adjusted as the Nitrates increased over time. However, if you throw fish that are accustomed to low Nitrates are suddenly tossed into a high Nitrate environment, well that's a MAJOR shock to their system and they will just get weaker and weaker and die.

 

Yea.. 88 way too high!!!! stresses fish out == dying fish even if temp is changed back.. changing it back will stress them out too!

 

you guys forgot the most basic, if all the cards are the same sex they will fight.

 

Well certainly. I've seen bad fish stores before but I would assume even a bad one would know to only put one long-finned cardinal with two short-finned cardinals.

 

I also blame the temp, lots of people call them begginer fish but they are really fragile and prefer lower temps 76º or below