I've been shifting around my current stocking (profile not up to date atm), and have begun to play around with the idea of adding an "eel" to my 120 gallon. I really like black spotted eels, and from what I can see they will not outgrow my tank. But I've got a few questions: What size fish is no longer in danger of being eaten? I plan to leave turquoise rainbow fish and pearl gourami with it and have seen that as long as the fish is bigger than the eels mouth they are fine, but I have no reference to how big their mouth gets, so will these be fine? My tank has sand substrate, but is pretty well planted. I mostly have a variety of swords and java ferns. The ferns are sitting on the surface so I don't mind those getting pushed around, but will the eels destroy the root systems of the swords? Still not sold on adding an eel, I just like the idea of it. Please let me know of any reasons to not do this!