yeah you could get a damsel or 2 in there or you could do some nano fish like firefish,jawfish and smaller gobies,keep in mind you shouldnt have more than 2 fish in there. You'd need a filter,substrate,decore/LR,salt,lighting,fish and test kits. Thats the basics but there is more I am just laying down the basics. When I started my 30g its cost me about 250$ without the tank(i already had it)