I bet you tank looks rather empty..... You could add several more if you chose and/or a small shoal of peaceful fish, such as neons or rasboras. Just make sure that the fish would not look at your frogs as a food item. I have 6 ADFs (1 male, 5 females) in a heavily planted 50g display tank with 30-35 small peaceful fish, including 6 small corys. The frogs have been in this tank for almost 6 years and continue to do well. Of course, if you plan to breed your frogs (I have read your post reagrding the eggs layed by your frog, and have responded to it), then you want a speices tank.