Hi, I've had my glass catfish for about 4 days now. At the moment I only have three. I plan on getting three more to make up the numbers since I know they like to be in bigger groups (they only had 3 left in the petstore at the time)
Anyway, I'm cycling my tank with tetra safestart. I did fishless cycling for a month and ran into lots of problems, however I think it did some good and my tank is in pretty good condition.

One of the glass fish is much smaller than the other two and has white blotches on its body. I remember seeing some when it was in the petstore but I think they may have multiplied. The fish itself is acting ok, a little shy but he's very keen at supper time. He also swims about quite happily at night with the other two. The other two seem fine and look very healthy. I'm keeping an eye on all the nitrite/ammonia/nitrate levels and they are as follows:

Ammonia: 0.25ppm
Nitrite: 0ppm
Nitrate: 5ppm

I know ammonia should be 0 but I'm cycling with Tetra Safestart which keeps the levels unharmful until it cycles.

What can I do? Is there something I can buy to medicate the fish, is it something that might clear up on its own or does it mean imminant death?
Like I said, the fish is acting healthy and has only just recently started fighting the others for food, its not acting like its sick but I have no experience with tropical fish diseases. Please advise.

*Please don't complain about there only being three. I will add more once the tank has had more time to mature with the SafeStart, hopefully 1-2 weeks.