All male tanks can work - but be careful of the species. It isn't that they fight for females. They fight for territory, which means food. They graze on the rocks within their territory, scraping the algae off. The alpha male just happens to be the one who holds the best territory, and is first choice for the females. Make no mistake - females are aggressive and territorial as well, especially if they are holding.
If you are looking for a colorful display tank, look into peacocks and other haps (who are open water swimmers). An all male peacock tank can look amazing! And the stocking density doesn't have to be so high. Look into the Placidochromis electra, Cyrtocara moori, Sciaenochromis ahli.
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