the dimensions are 15 inches the height, 24 inches length, and 12 inches width. i was thinking some corries because i just converted my gravel tank to a sand and planted tank. I was going to rotate the apistos in and out of the tank from my 75. But i will have 1 pair in the 20 gallon first and that will be agasizii fire red, and the other that will start in the 75 will be the agasizii double red. The corries will stay in the 20 gallon permanantly. but i was thinking of 1 or 2 corries. or something that apistos will go well with. The apistos are the main fish but i wanted a cory or 2 to help with the sand and stuff.