No, they sill cannibimize each other, this is nature, there is no way for you to manage this. It may happen immediately, it may take a year, if it doesnt happen, then you are one in one thousand.
A 20g would be fine for one of the smaller anglers, like a warty, or a pair of pygmys. Keeping a couple of wartys together may be possible, although I would not do it, I have seen these guys eat each also. These small ones dont seem to be such aggressive eaters and many times try to eat things at least a bit s.aller than themselves. So you have to manage their growth to be equal to each other.
It's not about keeping them well fed, they are insatiable, and will eat themselves to death. They can and will eat something equal to their own size and will attempt to eat something even larger. This usually ends in both their deaths.
At the end of the day, its not a good idea.
