I presently have a 6-gallon tank in my 2015 G3 1652. Only one I have tried is a 10 gallon. It is too tall to fit in the space available, unless I remove my added-on hatch cover. I feel I need the cover for when a back-seater fishes on the small deck, he needs some additional space for his feet. It is the bracing underneath the area that pushes the 10-gallon tank up too high.