All My Fish Are Dying

[daiandgems]

Hi there, any advice concerning the following would be really appreciated.

About ten days ago we bought two Dwarf Acara Cichlids that quickly caused havoc in the tank (chasing anything that moved and patrolling bottom of the tank), we promptly took them back to the shop we had them from and exchanged them for 3 Boesmani Rainbows. Since then the fish broke out in white spot (due to stress I am gathering caused by Acaras) others are now displaying signs of mouth rot, fungus on bodies, gasping for air. We have lost four rummy noses, 1 peacock goby in the last five days, despite treating with Myxazin.
The remaining fish are 2 Peacock Gobys (neither look very healthy), 2 Odessa Barbs, 5 neons (2-3 look poorly), 3 rainbows and a plec.
Prior to adding the Acaras and subsequent rainbows the tank had run perfectly for around 6-8 months. Just wish we had quarantined the new fish before adding, but obviously too late for that now.

I have just done a water tests and got the following results:

Amonia: 0
Nitrite: 0
Nitrate: 5.0
pH: 7.6

Not quite sure what to do now. Would you consider taking healthy fish out and moving to our backup tank and draining tank and starting again as something has taken quite a hold in there?

Really appreciate any advice, thanks!

 

[rdp50734]

Gasping for air usually means low oxygen. Is there enough surface aggitation?
What size tank is it?
Have you been using any aerosols or something that could have contaminated the water?

 

[daiandgems]

There is an air-flow 2 air-pump running constantly and plenty of surface aggitation.
It is a 90L Fluval.
No aerosols used.

 

[rdp50734]

You could do a really big water change 80% wouldn't hurt, what temp is the tank at?

 

[daiandgems]

Thanks for your replies.
The tank is running at about 26C.
Was considering a big water change, like you say it wouldn't hurt and couldn't do any worse thats for sure.

 

[»äshleÿ«]

I would treat the whole tank. Your tank is cycled, correct? When was the last water change? Do you use any aquarium salt? 1 taablespoon (approx 15mL) of aquarium salt for every 5 gallons will help add essential electrolytes and help with intake of oxygen in water. Make sure you pre-dissolve it before adding to your aquarium.

 

[daiandgems]

The whole tank has been treated with Myxazin as previously stated in original post.
The tank has been running since May 2009 so yes as water stats indicate tank is cycled.
Don't want to be adding salt to the tank as I have a Plec and they don't tolerate salt well.

 

[rdp50734]

Im not experienced with diseases but I would raise the temp slowly to 29C for the ich. Large water change, and if you have mouth rot/fungus then I'd treat with PROTOZIN it treats whitespot and fungus. Thats about as far as I can help. Good luck to you.

 

[»äshleÿ«]

Yeah, true that plecs can be sensitive, but a small amount of NaCl (true aquarium salt, nothing with added minerals like marine salt) will be very beneficial right now. The only problem with a water change is that it won't really be effective unless the parasites are in their free-swimming stage. Too many WCs right now could stress the little guys out even more. Agree with the temp raise; ich can't breed in a temp 86 degrees Fahrenheit or more and most fish tolerate it really well. Just make sure there's a bubbler or the filter is running full force so the output helps oxygenate the water better. I'd wait until the spots start disappearing then start doing frequent WCs.