All My Fish Are Dying, Help!

[x..Lula..x]

Ammonia = 0
Nitrite = 0
Nitrate = not sure of exact value, had it checked at local fish store yesterday and it was barely present.
pH = 7.4

I have a 220 L fluval tank, my fish are:
8 Guppies
2 mollys
2 platys
1 clown loach
1 cory
1 plec
1 leopard danio
1 emperor tetra

I do a 20-25% water change weekly. The tank has only been running about a month as i recently upgraded it, i have been keepin an eye on the ammopnia and nitrite but there hasn't been any spikes, they have always been 0 or nitrite has been 0 - 0.25ppm.

The tank is well planted and aerated.

In the past week i've lost 7 emperor tetra and now i've lost 3 guppies.

My tetra developed a silvery/white discolouration starting at the dorsal fin which worsened rapidly, going down both sides, the affected tissue then appeared pinkish in colour.
My guppies have developed the same thing except on them it has started at the base of the tail and is moving along the body, destroying the tail.

I've tried putting the affected fish in salt baths but this has not helped. I've had a look online but can't really seem to find anything definitive as to what it is or how to treat, please help before my tank is wiped out.

 

[WILDER]

It sounds like columnaris if it started at the dorsal fin and went down the sides to from a saddle shape.
Also columnaris can show it's self in a pink colour. Does it look fluffy.
Any signs of flicking and rubbing.

Clown loaches shouldn't be kept in less than a group of three. Need 100 gallon tanks as they grow bigger.

 

[x..Lula..x]

It sounds like columnaris if it started at the dorsal fin and went down the sides to from a saddle shape.
Also columnaris can show it's self in a pink colour. Does it look fluffy.
Any signs of flicking and rubbing.

Clown loaches shouldn't be kept in less than a group of three. Need 100 gallon tanks as they grow bigger.

It doesnt look fluffy and i haven't really seen them flicking or rubbing. I've noticed one of my guppies in the tanks tail has got red streaks in it and one of his fins is not really wirking, he's just holding it out to the side. Not sure if this is same thing as the other fish have had or if its something else.

I did have more clown loaches a while back but they died and i never replaced them as i knew i was upgrading tanks. He seems pretty happy on his own

 

[WILDER]

Its sounds like a severe bacterial infections, Columnaris can cause finrot and septicemia.

Whats your location for a med.

 

[x..Lula..x]

Its sounds like a severe bacterial infections, Columnaris can cause finrot and septicemia.

Whats your location for a med.

I'm in Fife, I've had a look in local fish shop but didn't see anything too impressive lookin on shelf, just really bog standard water treatments.

 

[WILDER]

You can use anti internal bacteria med by interpet and pimafix.
You need to get treating fast.
Lower temp by a few degress so the bacteria dosn't muliply so fast in warmer temps.

 

[x..Lula..x]

You can use anti internal bacteria med by interpet and pimafix.
You need to get treating fast.
Lower temp by a few degress so the bacteria dosn't muliply so fast in warmer temps.

Thanks, how low should i put it? Don't want to sort out the bacteria but freeze my fish to death.

 

[WILDER]

Should tell you on the med instruction bottle how much to add to your tank size.

COLUMNARIS
The hospital tank should be heated to approx. 74 degrees. 76 and above is the ideal breeding temperature for columnaris. Though there is some dispute over lowering the temperature, my experience has been that 72 is too low for the medication to work rapidly, 76+ causes the disease to breed more rapidly than the anti-biotic can kill, and 74 is "just right." Remember to keep this temperature stable!