I have 6 eels in a 46 gal bow front tank 2 peacock about 5 inches each, 2 Indian green about 3 1/2 each, and the other 3? not sure, 1 (my personal favorite) is a piebald, he's about 6 inches long but the daddy (maybe momma) of them all is about 7 inches now with a hefty body but seldom get to see her, and 1 more that is about 6 1/2 inches long. Have had no trouble between any of them. I have 2 small oscars. 3 Madagascar Rainbows a balloon molly and a tiger barb in with them, along with a pleco, and an african sail fin cat, oh I almost forgot the banjo cat. Have had the tank set up for 6 months now and other than the recent long fin oscar I added all have been doing great. I run a Marineland 150 and an aqua-
clear 50 along with an old school corner filter and an air stone. I do a 25% water change every 5th day and add a conditioner after each change.
Yes a bit over crowded but... Oh, I did forget one fish I just added a 3 inch electric blue cichlid. But only because he's too small for my cichlid tank.
But as for the eels? they all get along fine I have lots of caves for them and the 2 peacocks are always together