Cause Of Death Unknown

[finfin]

Please help shed some light on my fish death...
I have been keeping tropical fish for approximately 4 years. and have had great success, but I recently started a new tank, a nice 46 gallon bow front from Oceanic.
I cycled the tank, using some Zebra Danio's (6)... I also had used some of my existing gravel in my Eheim canister filter too help get things going...all the parameters looked perfect as far as I could tell,
pH: 7.0
ammonia: 0 ppm
nitrite: 0 ppm
nitrate: 20 ppm
kH: 120 ppm
gH: 90 ppm
tank temp: 80.5

Fish Symptoms (include full description including lesion, color, location, fish behavior): hiding, then death

Volume and Frequency of water changes: newley cycled tank with no load.

Chemical Additives or Media in your tank: API stress Zyme, Kordon Amquel+, Kordon NovAqua+, API Aquarium salt.

Tank inhabitants: 6 Zebra Danio's, 3 rasporas. (2 Zebras, now died)

Recent additions to your tank (living or decoration): 4 Angel fish (died in 36 hours)
2 black mollies (1 died in 12 hours, the 2'nd in 36hrs)
2 Gurami's (1st died in 12 hours, 2nd in 36 hrs)
1 pleco

Exposure to chemicals: no

Digital photo (include if possible):no
The rest of the inhabitants, are flourishing, and are very active...and have no signes of any desease.
I have a gut feeling as too what transpired, but cant be sure.
the 4 Angels were the first too be added, after the cycle period, 2 died within 12 hours, the other 2 died after 36 hours)
.If these angels were deseased, and poisoned the water, why are some some of the danio;s no affected.
I know Danio's are Hardy fish, but still?
I have checked the Oxygen level, and is at 7 ppm, and checked the salinity of the water too, which is also right on the money.??
Please help, this is a beautiful tank, but dont want too kill any more fish.
Do you think the Rasporas, are killing the fish, there really quite aggresive?

 

[WILDER]

What the lfs ph to your tank, and how long do you climatise the fish for.
Any signs of laboured breathing or flicking and rubbing against objects.
Check the gills to see if there pale or have excess mucas on them, also check to see if there red and inflamed.

 

[finfin]

What the lfs ph to your tank, and how long do you climatise the fish for.
Any signs of laboured breathing or flicking and rubbing against objects.
Check the gills to see if there pale or have excess mucas on them, also check to see if there red and inflamed.

Thanks for taking the time too look at my Posting..climatise for 1 hour (prick hole in bag too slowly equalize, before release.)
No labored breathing, no weired behaviour, just death.
the Mollie did look iffy, but the Angels were good looking even after death. No signes of any parasites.
Gurami's were shy, but were eating when fed, but they died also... I dont understand "lfs ph". what do you mean?

 

[WILDER]

Because with the deaths happening so fast is sounds like you are not climatising them properly.
You always need to know your lfs ph that they are keeping the fish in to your tank ph.
As if there a big difference it can't take hours to climatise them.
Do the fish dart around and spin when you let them go out of the bag, and stay at the top of the tank.
Also its always wise to quarantine new fish.

 

[black angel]

lfs ph = local fish stores ph value of the water.