Glass Catfish White Spots

[CrackFox]

Does the medication indicate whether it might affect the biological filter? If it does, than that means you are trying to fight an illness as well as not growing any bacteria in your filter because the meds are killing everything off - hopefully that's not the case.

It doesn't say anything like that in the instructions. I also don't have a carbon filter. Things still very much the same. I haven't got much of a look at the sick fish, he spends a lot of time in a little house with his buddies and I only really seem him when he comes out to feed. The other fish are looking great, which is a huge relief. I'm hoping whatever it is the sick fish has got it wont spread to the others, I think it would have done so by now if it was going to.

@ddavis1979: I'm not using a carbon filter and according to a calculator my current stocking level is 57%. I'm monitoring the levels everyday. I did a water change 7 days after I put the fish in, I did this because the ammonia was creeping upto 1ppm and even though Tetra says that the levels will gradually reach 1ppm then come down themselves, I felt uncomfortable with the level that high, especially with the sick fish who was already suffering. I did a water change on Saturday night, added more SafeStart and I haven't changed it since. The levels are stable.

Ammonia: 0.25/0.5ppm
Nitrite: 0ppm
Nitrate: 5ppm

They seem happy, no gasping for air or damage to their fins so I think they're doing fine. I will rejoice the day when my tank finally cycles.

*I think I may be overfeeding, not that they don't eat every last bit but it seems like a lot. As soon as I open the lid to test the water they swim up thinking it's feeding time, even though I'm sure they're eating plenty. I'm using Tetra flakes right now but i'm going to start feeding them bloodworm pellets as well. Should I wait until the tank cycles before I start introducing new things to their diet?