That is WAY to small. They are jumping because they are stressed out. I am can guarantee you any petstore you buy frogs from will provide you with really really bad care advice.
You should honestly split the frogs up my species into plastic tubs with wet paper towels. Use Distilled Water. Tap water is toxic to amphibians.
I wont sugar coat this, if your frogs stay as they are for very long you will slowly start to loose them. I am offering you advice that will allow you to enjoy your frogs for years and years. Each species needs to be in a tank by them selves. 18x18x18 is plenty big. Until then keeping them in a temp/QT tub like I described earlier will be your best bet to calm them down and keep them happy. You should honestly do the move no later than this weekend. 9 days without eating is pushing it. You can use cheap tubs from the dollar store or buy some $5 tubs at a big box store.
QT Tub
1 - Layer unprinted paper towels on bottom of tub (2 deep). Make the paper towels as flat as possible
2 - Add some plant clippings. Pothos or wondering jew work good in these situations
3 - Something to hide under or in. A deli cup works if that is all you have or piece of cork, coco hut. Anything that is non toxic and wont mold in a humid tank
4. Distilled waster. Soak the paper towels. You dont want it to be laying in water but you want them saturated.
5. Mist with Distilled water 2 - 3 times a day or as needed
6. Feed daily. Place a piece of sliced banana into the tub. The flies will be drawn to it and will help minimize escaped flies.