I'm hardly a newbie and I know exactly what you are talking about. I've worked with aquarium fish as well as other animals...wild, captive, domestic etc. for many years. I don't see much aggression among eels except during feeding and that's usually with SW
eels not FW
eels. We keep them together all the time. Feeding SW
eels is a blast, though we need to watch them. I've pulled a couple of SW
eels out from another's mouth before...and bit in the process...lol. Once feeding is over, they're all hanging out under their caves all tied in knots with each other.
Eels are aggressive with other fish because they try to eat them and mature males may fight with each other during certain times of the year. Occasionally there will always be that once in awhile blood bath from a tweaked individual, but I've never seen it nor have heard about them often. If you packed them in a very small tank and not feed them well, then yeah...they'd fight and eat each other. Otherwise, they seem to be rather content not to expend the energy and continue digesting their previous meal.
We, as a people, know so much more about outer space than we do about our own oceans. This lack of knowledge can very well spell the dangers that lay in wait for us.
The oceans surely would swallow us before a rock comes down to smite the planet of it's life.