[mr_kgeorge]

Tank: 4'x3'x3'
Filtration: 2 x Ehiem 2262
Medium: 2″ Poret 10 PPI
2″ Poret 20 PPI
2″ Poret 30 PPI
Biohome Maxi Ultimate
Chemi-pure Elite
Powerhead: EcoTech Marine VorTech MP40wQD - Set on Reef Crest Randon Mode
Livestock:
1 x giraffe catfish (Auchenoglanis occidentalis)
6 x Synodontis angelicus x eupterus hybrid
12 x Synodontis petricola
1:4 Red/pink Blood Dragon (Aulonocara sp.)
Heater: 4 x Cobalt Aquatics Neo-Therm 200 Watt Aquarium Heater - Set and maintained at 78
Décor:
100 lbs CaribSea African Cichlid Mix Aquarium Substrate
100+ lbs of Lava Rocks

This tank has been set up for 2 months. Fish have been added past three weeks, not all at once. I perform a 25% water change every Friday. Water perimeters of the aquarium before water change is the following:
pH: 7.8
Ammonia: 0 PPM
Nitrate: 0 PPM
Nitrite: .5 PPM
My house has a filter (Pelican carbon series whole house water filter system) and softener (Pelican NaturSoft salt-free water softeners) system so I use filtered tap water for the water changes. The tap water is at 7.8 pH.

I noticed 24 hrs after every water change the female peacocks move to the surface of the tank and they look like they are gasping and struggling. After another 24 hrs they went back to normal behavior. Friday, 11.2.2018, I performed a 25% water change, Saturday morning all the fish were behaving normal. Saturday at 17:03, all the females were on the surface, I didn't think anything of this and at 19:08 I found the 9 x S. petricola and 5 x blood dragons dead. I removed the remaining fish and tested the water. Everything is normal. Does anyone have any ideas or thoughts on what could be going on? I am stumped.

Thanks for your help and guidance in advance.

 

[noddy]

How did you cycle your tank?

 

[mr_kgeorge]

How did you cycle your tank?

Fishless cycle.

 

[mr_kgeorge]

How did you cycle your tank?

Fishless cycle.

 

[DJRansome]

You should have no nitrite and you SHOULD have a nitrate reading. Did you use dechlorinator?

 

[zimmy]

You should have no nitrite and you SHOULD have a nitrate reading. Did you use dechlorinator?

+1 Your readings mean your tank is not cycled. Fish gasping at the surface is usually a sign of nitrite poisoning.

I would check the parameters of your filtered tap water. The reaction of your fish AFTER a water change makes me suspicious about it.

I would increase surface agitation with a power head and try double dosing with something like Seachem Safe. Also, stop feeding the fish till your nitrite is 0 and you're getting a nitrate reading.

 

[ironspider]

Tank isn't cycled properly. Nitrite should always be zero. You should see some nitrate as nitrite is converted.