The 16 and 210 don't have lids. The water level in the 210 is always 2" below the top, and it has a eurobrace, so it would be more difficult for the Polys to jump. Along with that, most of them are lazy. The Sens and Koliba sit on the bottom, the Ropefish hides in a clear tube I got for the Black Ghost Knife, and the Ornate always hides under the driftwood.Angelphish is this tank your 210g? The one with no lid?