Help with sick fishes

[acker16]

I have a 100 liters aquarium filled mainly with tetras about 3 month ago the fish got an unidentified disease and a few dozens died , about a week ago( after more than a month without fatalaties) I bought some new fish and the very next day 2 emperor tetra died and my glu-lite got some white discoloratiob on their backs and stomach - I realy need to indentify the cause because it seems that waiting the disease out doesn't work
I'm attaching pictures of the discoloration
Please Hurry

 

[WILDER]

Going pale and losing colour can be stress, so first off can you please post test results in ammonia,nitrite,nitrate,and ph.

 

[acker16]

I don't have these kits but I can check the pH tomorrow - as I shown in the pictures the discoloration is local , and stress-discoloration is more general

 

[WILDER]

Like to see your stocklist in what you keep in the 20gal, which fish and how many, i would do a water change for now, get water stested as soon as possilbe and do you keep neon tetra's in he tank.

 

[acker16]

I currently have a few glu-lites a few congo tetra , rasboras, emperor tetra , black neon tetra and techinidis(I probably spelled that wrong) and a clown loach.
I'm thinking maybe the emperor tetra died from stress but the others ...

 

[WILDER]

How big is the clown loach as they need a 90gal tank, you will have to say how many of each tetra you have, you sound overstocked and i almost will bet it's bad water quality, so i would do a water change, are they heavy breathing and gasping at the top of the tank.

 

[WILDER]

Forgot clown loaches don't like to be on there own need to be in groups to be happy.
http/www.fishforums.net/index.php?showtopic=34953

 

[acker16]

First of all I Recalculated the volume of the aquarium and it's about 140 liters /30 gal. UK (or 36 U.S.) . Second , I know that clown loaches are schooling fish and was planning on buying two more but since this disease I'm not sure it's a good idea.
Third ,I'm pretty sure the water quality is fine - I have a RENA external filter (1000l per hour) so I'm guessing I'm covered. still I'll check pH.
fourth , I have about five of all the other fish , but my ultimate goal is to have about 5 schools of 10 fish each + cleaners ( I forgot about them )

 

[acker16]

New Info: The pH is 7.88 but it should come down in a few days because I attached a crude DIY CO2 system
The Temp. is 31C/88F but Ican't lower it because it's my room Temp.
I would Really appreciate any help or tips anyone could give.

 

[WILDER]

The white patches on the back and stomach sounds like this is it fluffy in appearance.
http/www.flippersandfins.net/flexibacter.htm
http/freshaquarium.about.com/cs/disease/p/columnaris.htm