Problems with medication for ich

Question
Hi!  I have a "situation" on my hands and I don't want to make a mistake!  You see I think my fish have ich or some sort of gill parasite.  I also have nemotodes in the tank that had just come back after disappearing for awhile.  They are rubbing up against things and its definitely obvious they have something bothering them.  I would just go to the store and buy medication but what is stopping me is that all the medication target invertebrates such as my precious crayfish and snails.  I don't quite know if there is another method I can use to treat the parasites in my tank!

Also my bullhead catfish's fins are looking a little bit rough recently.  My other catfish's fins are fine so I don't know if there is something going on there.  They are rather agressive for bottom feeders (not only will they eat anything they can fit in their mouth but they don't know the meaning of "full") and sometimes they have a sudden burst of excitement knocking things down and speeding around the tank and then just stopping again.  I hope thats just normal for their behavoir becuase they arn't necisarely normal catfish.  Also I'd like to mention I it is a 30 gallon tank with plenty of filtration and decent heating.

Thank you very much for reading this and I hope you can help me with my situation.

Answer
Mike,                                                        Go to the pet shop and get coppersafe. It is mineral based and stays in your tank fpr 30 days. No need to rermove your carbon. 1 tsp per 4 gal. Flashing or scratching is a tell tale sign of parasites and they do gather by the gills and try to suffocate the host. The only prob with this is it may kill your crayfish...MAY....Feed your catfish more.... something like beef heart.... you can get that at your pet shop......Sometimes they dart around if they don't have enough room..too......treat for 30 days then new carbon and at least a 30%water change... Good Luck Tina