I've seen a lot of spiny Eel community tanks with as many as a dozen similar sized Eels the people will tell you "don't like other eels" and they swim all over and around each other, I wouldn't be worried about them fighting so much as the bottom getting over crowded, I may skip the royal pleco and try out a TT, a Fire, and my BGK, it's going to be close to a year before I can afford to set up the 350 the way I want it, so this is subject to minor changes along the way!Is a 350 big enough to keep the tire track and fire together? Is the concern they will fight?