It's less than optimal and i have been told no less than a 40 gallon for cichlids, but i think u may be able to get away with 3 of a smaller species. but dont quote that,
You could shelldwellers, they're suposed to be great fish with intresting behaviour so you aren't missing much, some sources tend to say there less colorfull but many do look great
A 25 gallon is very possible, but you should look toward lake Tanganyika, rather then malawi. Malawi fish tend to be too big or too aggressive for small tanks. There are a number of Tang rock and shell dwellers you can choose from.