Procedure to follow after a fish dies?

[squirrelrabbits]

I've never had a fish die, but I just lost an elephant nose that I dumbly brought into the house that I believe (now) was diseased... Anyway, I am wondering how to deal with my other tanks and fish. When I brought him home, he had a horrible tail malady (total tail rot) that somehow we issed at the lfs, so I placed him in the hospital tank with a Gourami. Before doing so, I had to do a 50% water change to get all meds out of the water (elephant noses are very sesnitive to medecine) and I put activated carbon in the filter for the same reason--to help get the meds out and give him cleaner water. While I did this, the E.N. was floating in his bag (top open) accliamting in another tank; when I lifted it out, I saw that somehow a small hole had been poked in the bag--so water from it unfortunately did mix with that of my established 30G (rainbowfish and loaches).

It's hard to diagnose the poor guy's malady. He seemed ok and even was curious in his new tank but his tail was bitten to a nub--I thought from a fight with another fish. Upon removal this morning, I noticed however that he seemed to have some internal bleeding on one side (skin is all red under the surface).

Question is: should I do a massive water change or anything else in the 30G or the 5.5 gallon hospital tank? The hospital tank has one other occupant--a wounded gourami, and I have started him back on melafix as soon as I removed the dead fish and I also removed the carbon from the filter once again in order to retain the melafix. Anything else I should do?

Thanks for any ideas! I appreciate all the help I've gotten on these boards.

Trish