Red rashes on fishes

[birman]

My brother has recently started another 4 feet tank. He didn't wait for the tank to be cycled and added several fishes and they died with body full of red rashes. I've tested the nitrite to be around 1ppm which is not high enough to kill in this way. Only 2 blue damsels are left. All butterflies dies in the same manner and has also killed my clown and gramma which I gave him. He has a Sea Apple too.
I wonder what's the reason for this symptom. Could this be the Sea Apple excreting poison into the water due to poor water parameter or is it due to something else?
50% of water change was done and the sea apple removed.
What is the symptom of sea apple poisoning?
What can I do to find out the cause and stabilise the system?

 

[e-cat]

forget the nitrite test the ammonia, it was probably a mixture of the sea apples poisoning the water and the tank not being cycled. saltwater=patients

 

[birman]

The ammonia is ok (0 ppm). Just the nitrites. What are the symptoms of sea apple poisoning and what's the remedy?

 

[e-cat]

i guess the ammonia didnt spike yet, not sure what the symptoms of sea apple poisoning are.

 

[birman]

so what's the suggestion now? Should I do another water change (how much?) and restart the whole tank cycle? :?

 

[e-cat]

i would read this about the sea apple first http://www.liveaquaria.com/product/prod_Display.cfm?siteid=23&pCatId=711 it says that sea apple should only be put in well established aquariums and not with fish that will pick there tenticles like butterfly fishes. if it where me i would take the fish back too the lfs and the sea apple and start the tank over right and get some live rock and live sand and get compatible spieces next time, good luck