What is this disease on my guppy?

[pyralis101]

I put 5 guppies in one of my tanks a month ago. Over the first week, one died each day or every other day - always at night with the light off. I noticed they all had reddish color in their gills. The largest of the 5 has lived 2 weeks past the others, but has always has the redness in the gills. My amonia is at zero, or I would have thought it was amonia poisoning.

Then today, I found this horrible spot/blister on my guppies head. There are 3 types of tetras in the tank and a beta, and all are as happy and wild as usual, so this has only affected the guppies. Although none of the dying ones had this spot.

Any ideas what this is and how I might save this little fella?

 

[Colin_T]

It's a bacterial infection.

Do a 75% water change and gravel clean the substrate.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

Clean the filter if it hasn't been done in the last 2 weeks. Wash filter media/ materials in a bucket of tank water and re-use them. Tip the bucket of dirty water on the lawn.

Add 2 heaped tablespoons of rock salt for every 20 litres (5 gallons) of tank water. Keep the salt in the tank for at least 2 weeks but no longer than 4 weeks.
If you do a water change while using salt, add salt to the new water before adding it to the tank so the salinity (salt level) in the tank remains stable.

Monitor the fish and if there's no improvement after a few days with salt you might need a chemical medication.