I had my four russians housed in a 125 gallon aquarium for ten months and they did very well. I installed an exaust fan in the top of the enclosure, the type used in windows. I do not recommend using an aquirium. I have since moved my tortoises into a 6' X 6' metal stock trough - the type used to water cattle. This works very well. I use a wood pellet animal bedding. Russians need lots of space to move around, and mine are very active.