Help! Possible Sick Spotted Raphael Catfish

[Livdumer]

Hello! Just over a month ago, I started up my first 20g freshwater fish tank. So far I have five cherry barbs, one dwarf gourami, a spotted Raphael catfish, and a beta fish. All has been going fairly well, but about two weeks ago I noticed a few of my barbs having long white stringy waste (which I read was a parasite). I then added a paraguard to the water which seemed to clear the problem. Although last night I caught a glimpse of my catfish and now he is very pale and seems almost skinnier than normal. He's been taking a while to come out after I turn out the lights when he used to come out right away. I'm nervous the paraguard might have hurt him, or could it be something else?? Just today I also noticed the stringy waste again (this time on my gourami) but I'm too scared to add the paraguard. I'm terrified I might be losing my beautiful catfish. Someone help!

 

[the_lock_man]

I have moved to the emergencies section, for better help.
 
Since your tank is only a month old, can you tell me whether you know what the nitrogen cycle is, and in as much detail as possible, how did you cycle the filter? Also can you post up a current set of water stats - we'd like to see ammonia, nitrite, nitrate and pH as a minimum, but if you also have KH as well, that would be good too.
 
I am suspecting that the tank/filter is not fully cycled, and this is what is causing the problems.