[Feathers]

I used to have seven Danios in a 10 gal, and in two weeks their numbers dwindled all the way down to two. I have been monitoring my water levels obsessively since the loss of the very first fish, and find absolutely nothing wrong with the water quality (aside from it being hard and having a somewhat high PH, but it's always been like that so I don't suspect that is what is killing my fish.)

Medications: Pimafix, Melafix, Anti-Parasite meds

Fish #1: This fish had stopped eating, which I assumed may have been from the two mollies that were quarantining with my batch of golden danios being far too dominant for the food. I removed the mollies as soon as I noticed said fish getting thin, and moved them over to my molly tank, only to see that the fish did not eat anyway. I took her out of the tank, isolated her in a 5 gal bucket to see if she would eat when there was no competition, but at that point she was already having trouble swimming, and she didn't last the night. (I had a filter and heater on the bucket...so I don't suspect temperature or water quality was the cause. Maybe separation from the other fish factored in?)

Fish #2: The second fish I lost was my smallest Danio. I should probably have covered the slats on my filter intake pipe when I realized how small the guy was, but I didn't really foresee it being a problem. One evening, I noticed a red mark on his side and wondered if it was from bullying, and found him the next day dead mostly inside the intake pipe. (It was kinda gruesome...) I had assumed they were strong enough for the filter to not be a problem, but whatever was getting them was making them pretty weak.

Fish #3: This one had stopped eating around the time I lost the first fish, and gradually got weaker and weaker until I found her dead in the tank.

Fish #4: This fish actually had something wrong with it that I could see. All the other fish appeared fine with the exception of the one that had the red mark on its side. This one had a lump between its anal fins, which I assumed was a sign of parasites. I had been treating the tank with Pimafix and Melafix prior to the lump developing, which then caused me to treat with anti-parasite medication. The lump went down after I began treating for anti-parasite, and on the day the fish looked like she was better in the morning, I returned from class to find her dead, as well.

Fish #5: This fish stopped eating shortly after the loss of fish #4 (along with one of the remaining two fish). I can only assume that it got weaker and weaker until it died, since I couldn't see anything at all wrong with it. I examined all of these fish closely after they died and couldn't find anything whatsoever wrong with them...aside from the one that got caught in the filter... This particular fish was simply very thin from not eating. It wasn't for lack of trying, either... it just wouldn't eat.

Of my remaining two fish, one has been not eating for as long as fish #5, and the other fish stopped eating yesterday.

I have been changing the water regularly (every day) in order to medicate and in hopes of getting rid of whatever is killing my fish. But...as it is... it doesn't look like these last two Danios are going to make it.

Does anyone have any suggestions? Even if there's no way to save the last two fish...I kinda want to know what happened (if anyone knows o_o) because I've never seen anything like this happen before. I asked a couple of the more knowledgeable people at my LFS, and they couldn't offer me any insight either.

My poor little Danios...