I have 2 tanks w/ red tail sharks. One tank has peaceful schooling and the sharks goes about his business with no problem on either side.my next tank has kinda agressive fish...tiger barbs znd a
betta along with 2 silverdollar and 4 lg goruamis. 1st tank is 55 gal and 2nd tank is 75 gal. They all getalong but I am sure the size of the tank does help piece or war.The
red tail shark is my favorite fish so i watcvh him close. I once added a rainbow shark to my 1st tand and jack (RTS) did notlike that one bit. He got real stressed, lost his color and became a coward..I took rainbow back to ltf and jack was his old self in 2-3 days...My recommendation would be to keep each tank to one type of shark..but the rest of his mates should just well if the tank isnt tosmall...Hope that helps.