mine are round 6 inches long. I should add though that years ago I had a gold severum that was almost a foot long and he lived just fine with a school of neons. I should probably also add that these two severums used to have a third friend (they were all from the same brood), but they beat up on the third. When I moved the third to my 75 gallon, which at the time held community fish, he began preying on all my swordtails and platties. The pair I have now also randomly attacked and killed my favorite fish, a 10 year old Featherfin Synodontis.
The pair I have now that started eating my danios live just fine with 3 breeding pairs of convicts, 3 blood parrots (1 breeding pair and an odd man out), and 5 Tinfoil Barbs (bigger than the severums). When I first added the barbs about 6 months ago, they were smaller than the severums, and the severums tried to eat them as well, but they were just too fast and eventually the severums gave up. Now, the barbs are the largest fish in the tank and nobody bothers them at all.
I'd seen them chase the danios before but I thought nothing would ever come of it. Then last night, as I was watching the tank the severums separated one from the school and herded it into a corner. Then they came in together about 3 inches apart, using one of the thick plastic plants to block the danios only exit. They then proceeded to grab his face and the tail and start shaking the poor danio. By the time I reached the tank with the net, there was no face left, no eyes, and no tail.
) but today they randomly started hunting and successfully catching and eating my giant danios. Just wondering if this has happened to anyone else.