Tank previously used for salt water fish...

[Mentat]

If interested in a Pacman, recommend read this care article: Frog Forum - Pacman and Horned Frogs - Ceratophrys - Care and Breeding. A 15-20H tank is too big for a Pacman; specially if starting with a baby. If so; recommend an ExoTerra Medium Breeder Box for any baby smaller than 3 in. In there you only need a layer of substrate (shredded coco mixed with dechlorinated tap until clumps in fist without dripping water out) as deep as frog is tall, a water dish filled with dechlorinated tap to frog's chin height, and a silk plant or two. You can place the whole box with frog inside a larger tank since it's easier to maintain temp and humidity parameters that way.

Once frog reaches 3.5 to 4 in. snout to vent length; than you can transfer frog to bigger tank (10G or an ExoTerra Small Medium (18 in. cube). Good luck !

[RedEyeFromMD]

oh by the way, the tank is 14"w x 10"d x 12"h

[Mentat]

That size would suit an adult space wise. You can always start a baby in a smaller plastic enclosure placed inside the larger one and release it after it grows up .