sudden deaths

[turquoisegirl1]

someone please help, have a tank with two discus, two angels and some cardinals. all was going fine for the first few days then lost a handful of the cardinal - begun 25% per day water changes, all was fine. replaced filter media today but left bio medium+balls in so that some good bacteria would remain in the tank. decided not to water change today, but in the last hour, one of the angel fish has fallen very ill. swimming in spirals, dont think i can save it. one discus is very dark in colour but still eating, breathing fine etc. no more cardinals have dropped and all the others seem fine - some pleease help before i lose my discus,
thanks!

[turquoisegirl1]

the dying angel is spinning in circles and freaking out, like its some kind of neural thing - will just keep dosing with salt at recommended dose and water changing every day until i get other advice

[AliH]

Have you tested the water? it may be an Amonia spike..With new media the old bacteria may still not have been able to break it down and convert it

[turquoisegirl1]

readings are slightly above 0, the only way to get them down is to water change the ammonia out yeah?

[swifto]

That's correct.

[ILLUSN]

sounds like you have a problem with your water my first guess is chlorine poisoining, are you aging your water before your changes (24 hrs of airation is enough) try and use Prime at a 2-3x dose.

the other thing i can think of that causes this is pesticide poisoining, have you sprayed or treated for roaches recently? do you use roach baits in your house?

have you checked for no2? its much more toxic then ammonia, if your reading trace ammounts of ammonia your tank might be experiencing a "mini cycle" detectable levels of NO2 will quickly kill fish.

[turquoisegirl1]

whatever it was, i decided to plant out the tank about a week ago and all of the fish have been fine and healthy since