I upgraded my 10gallon brackish into a used 20 gallon tank. The previous owner cleaned it really well with a scratch pad, that apparently was not meant to be used on this type of glass LOL. That's why the glass is kind of foggy. Also the water hasn't settled completely.

It contains a male and female fiddler crab, five adult mollies, several baby mollies, one dragon goby, and one bumblebee goby. Also a ton of Malaysian trumpet snails. The plastic container under the rocks is so the fiddler crabs can get some air.