Old hen, sounds like an okay way to cull, if not a bit expensive and I wouldn't really want to waste my fungal medicine either, but I will definitely keep it in mind. Thank you. I really don't mind culling fish that cause stress or damage to the tank, and sometimes it is neccassary to take less desirable measures, such as the sock and hammer. There are some humane ways to cull but not everyone will like all of these: Sock and hammer: insert fish into sock, rag, paper towel, etc. and hammer hard, then throw whole thing out or wash sock/rag if used Decapitation: use plant shears or cutters, you can even use scissors, and slice off the fish's head, disposing of the body Euthanization: kill fish with overdose of fungus medicine or something similar Reuse: feed fish to other animals or bigger fish Quick killing: either snap the fish's spine or crush their brain case These are different ways to cull, not all desirable. Some may say that culling fish for aggressiveness is cruel, but what will you do? Rehome them to someone else's tank where they will certainly wreak havoc? Let them kill your helpless, passive fish? Keep them solely and let them take over your tank? It is time to take action when fish come out of line.