Im trying to picture this 55 gal tank of yours loaded with LR just below the water line. It kind of tells me it crowded as it is alone just with the eel, but also another type of problem could come up from this and its caused by dead spots in your water currents that surround the LR that is in your tank. What it is, is it causes damage to your LR by killing areas of the LR and the way you can tell this is you will see a white film dust covering parts of your LR and this causes you’re your nitrates to rise, if your nitrate levels are at zero, it will be at 20 ppm and this also will cause your Ph to content drop on the daily bases, that you would need to dose a small amount on the daily bases until you correct this type of problem. This I tell you if you see the systems of which I had explained to you.
So in a 55, I know you seen others having a SFE in a 55, it not mean that it’s the correct thing to do, just because the eel can fit for when the SFE is 30", it has nowhere to were it could swim too and on top of it, you will want to have as many fish you could, you want that, yes?
You show in your data info below your post that you’re a 100 gal tank, why not in there have the eel, and why don’t you select a section of medium size fish you would like and from there you can get your answers, responses from other members of the fishes that might do better with your SFE. You see, you need to meet up with your fish selection pick halfway, not just sit back and let others decide for you.
If your to have the SFE, I would go with nothing smaller then a 75 gal tank, never a 55, I never ever agreed with such a smaller tank to cage a 30" plus eel into.
