The rule of thumb is any tank over 100 gallons>2 males each side and 4-10 females.
NOW with that being said. You can get different results with these guys. The first time I got some of these fish, I went to a local place in Chicago (king Coral). He had some fully grown that someone brung in because they were the wrong kind.

I jumped on them because how often do you see them for sale at that size localy. I took them home and put them in my 75 gallon with peacocks and mbuna's because it was unexpected and I didnt have a tank ready for them

I thought that would be a big problem. To my surprise the big male got a spot in the tank and started displaying. :thumb:
I also saw just last week in San Diego where I live now, and Dan at Pet Kingdom has some mating in a 40 gallon :-? . He took some other more agressive fish out and they colored up. :thumb:
Right now I have a 125 gallon with two dominant males and the long fin tetra I bought to make them feel comfortable (for feeding when I first got them) can go right over to either one of them, flash his side and punk both of them lol. :lol:
So whatever you do, you can win or you can loose. :? Just keep in mind they not only need space for there burrows, they also need an area to get sand from to build it. They dont just push sand from one spot to make the burrow like some mbunas. They grab sand from some other spot in the tank to build it and then shape it. Very nice to see.

opcorn: