need a 2nd opinion

[louisrodriguez2011]

I need a 2nd opinion. I got a 125 g tank with (1) 10" Albino Oscar (1) 6" Jack Dempsey (1) 4" Green Severum and (1) 3" Redtail Shark, My son give me his 3 fishes they are (2) 10" Oscar and (1) 6" Jack dempsey. I'm planning to put them all together in the 125 g tank. you think they be good there? or they will kill each other.