How large is the Tesselata and how large are the other eels? You can't watch them 24/7 and especially at night when they'll be most active and most likely to harm each other. One day (or night most likely) the tessy will be large enough and either hungry or aggressive enough to kill your other eels I've only had one eel killed by another, a G. moringa that was harassing a larger M. melanotis (very similar to a Brazilian dragon). One morning I found the moringa bitten neatly almost in half, with only the dorsal fin connecting the head to the rest of the body about 6 inches behind the eye. That same melanotis almost ate a jewel moray about half its size. It chased the jewel around the tank and I had to remove almost all of the rock to get the jewel out. In both cases there were warning signs, the moringa constantly harassed the melanotis but the melanotis didn't really respond to the harassment until I found the moringa dead. The jewel I was lucky enough to save, but I acted immediately when I saw the melanotis actively hunting it.
I guess what I'm saying is be careful. I'd hate to see you lose a fish you've had for so long.
