You could do a Mudminnow and Topminnow tank,....or a Orangespot sunfish (or Northern longear or Bantam sunfish) and Tadpole madtom tank, or if you want to use powerheads and a chiller in the summer a darter- topminnow tank. Just dont do what i did and put bigger sunfish in a tank too small I has some Green sunfish in a 39 gallon and they killed everything .
