Dat question?

I have a 180g tank with 1 Oscar 12in, 1 male Chocolate 11in, 1 Blue Acara 4in, I started off with 2 Ntt Dats 3in, and 1 Indo Dat 3in. I have had them for a good 6 months and everything was fine, then 3 months ago one of the Ntts was beaten up by another dat and died from injuries. So my question is, it's been about three months with having 1 Ntt and 1 Indo (both are about 4inch) in the tank and I know 2 is not a good number. If they have been peacefull this long do you think it would be an issue, or should I get another To make it 3 again. The problem with that is just adding 1 to the group might be tough, so I would almost have to get 2. I would like to keep it as is but wanted your opinions. Thanks very much!

Any opinions guys? I love these fish and last thing I want is a blood bath. Thanks I appreciate the help!

Thanks guys, when raps has ntt's again I will grab one, then find another 2 Indos. Thanks guys