killer cory cat?

Question
My son has a 29 gallon freshwater tank in his room. About 6 months ago we added what we were told was an albino Cory cat who was apx 1&1/2" inches long. Now he is apx 4-5" long. How is he getting so big? He is eating all our fish. My question is, is this gentle bottom feeder actually killing them? Healthy fish started disappearing at an alarming rate apx 2 months ago, with no skeletal remains what-so-ever. The only fish left, of the original 20 in the tank are one zebra danio, one algae eater and one ruby tetra. Our yr old Loach, who was originally three times the size of the catfish was the last to disappear. I've done water changes, tested for ammonia, nitrites and nitrates, all of which were fine, in case the fish were actually dying and the catfish was merely cleaning up for me. I've purchased 9 zebra danios on two separate occasions and within a week they are all gone. They are fine all day on the first day and the next morning 3-5 are gone. After this they disappear one-by-one overnight, all except the original surviving danio. Is a killer Cory Cat possible, and can one possible kill and eat 4 danios overnight? I had to isolate a killer gold gourami and rearrange the tank once after he killed several fish, but you could see the gourami attacking the fish for days before they died. It worked, so I'll do it again if it will work, but I've never seen this catfish chase anything. The literally disappear overnight. Thanks for your input.
Brenda

Answer
Hi Brenda
I just saw your question in our question pool.

Any chance of you sending a picture of the "cory cat"?  If you can, send it to christiie911@yahoo.com and just put fish picture or something so I know it's not spam.  Cory cats don't usually grow that big, especially that quickly.  And, they're a very peaceful fish, I've had bunches of them over the years, never once a killer one.  I'm wondering if maybe you were sold an albino channel cat instead.....Send the photo if you can.

Christy