The tank is 8x 2x 3ft wide. In my experiance in keeping ca communities you'll have better success if the fish are introduced as juverniles. I don't think it's very wise to add adult fish to an existing communitee, unless you have a very large tank. I'm not sure if that size tank will work in the long run for some of the vieja you have, as you know they grow very large. Adding some dither fish could take away some of the aggression. I do use some of the smaller centrals as dithers in my tank, eg multispinosa, cryptoheros. As for feeding lettuce, i started them at quite a young age, it could be hard to get them on other foods if they're not accustomed to it. You could try pieces of cucumber or peas with the skins taken off. I hope this helps......nutty.
