lol, here we go. The Carapo is a different species completely than a Zebra.the first pic is a Carapo, but not a zebra. Gymnotus carapo (Carapo Knife) Gymnotus pedanopterus (Zebra Knife)
Tiger knife's and Zebra Knife's look very similair when Juviniles, but when adults, the Tiger is more than twice the size of a zebra, and has more of an orange color and faded stripes. Trust me.
Ok, you're right about carapo not being the zebra. carapo is the banded knife. As far as zebra, some books call coatesi the zebra while some website call pedanopterus the zebra. I don't really know which is correct.
One thing for sure is the tiger is different than those three mentioned above. Coatesi, pendanopterus, and carapo look more closely alike.
The above site is the only place I trust in identifying knives. You should go throuogh the site to check out the study and research and other knife species.
The one in your avatar got spots on its face, hence a tiger. If you can post more pics of it, like you said you are gonna, we should be able to identify it better.
I have been working on the tanks, and moving and switching things around. I had to take the E. humboldtii out of the 60-Gallon again. It all was going good for about to weeks, but the BGK just got too aggressive. Two fish with an electric organ do not get along, unless of the same species. So, what I plan to do is put him in a 40 Gallon with the Zebra (And a few others). I'll post what happens... maybe some pics also...