My brother is currently setting up a 120g (24”x24”x48”) tank and after seeing my BGK has really decided he wants to get a knife of his own, right now the tank is cycling with just some sand/rocks/manzanita wood in it. I gave him an FX6 to filter and soon I’m bringing him a ton of easy plants (swords, Val, crypts, mosses, Anubias) to add in some life before the fish. I’ve only ever had 1 brown knife and it was in a 55g with a feather fin cat and nothing else. So my question is stocking for the tank, he wants to have 3 brown knives and I’m giving him a feather fin cat and a green Severum. Can 3 brown knives coexist in 120 gallons? I’ve only ever seen knives kept with 1 knife per tank. Would the set up of 3 brown knives, a featherfin, a green Severum and probably some giant danios, work in this tank long term?