Nurses Do It Better
Technically Serrasalmus species are solitary fish. It is at what cost you are willing to put up with such an experiment. Hey, i've seen it first hand a shoal of elongs packed in a 20 gallon with no fin nips....It's all up to you...People will tell you no, others will say go for it...I doubt Sanchezi or any Serra would successfully shoal without a very large tank. My experience is that it will destroy anything that moves. When i had mine in the 55 i had a pleco 3 times his size and he still killed it by drilling a hole through his head.