According to the conversion calculator I found, you need closer to 37 liters (10 Gallons). Of course what you have is bigger than the 5 Gal I'm using atm (18 liters according to that calculator.) so it should be okay until or if you can get something bigger.

I'm not an expert, but this is what I've learned:

77 F(25 C?) should do the trick on temperature.

Feeding depends on how old your frog is, if he/she is kinda small, every other day is good, but from what I've seen every 2 - 3 days is okay for a full adult, but I wouldn't go three days between too often. I also do a 20% water change with a gravel vac on feeding days (I feed every other day). Just wait a bit for the frog to eat(I give mine a few hours because he has a few special feeding needs from poor care before I got him) then suck it and any other extra junk up as well(I use frozen cubes, so it all sinks and spreads, if you're using floating stick you can scoop it all out, but I'd still suggest a gravel vac for getting waste out while you're at it). It helps keep the tank clean between full cleanings.

Substrate should not be small enough to fit in the mouth or should be fine like sand to help anything swallowed pass through. Pea gravel can cause impaction and death, I use large decorative stones I originally got from a hobby store then scrubbed and boiled to clean. Large round rocks scattered with some spacing so that you can see the bottom of the tank in most places helps keep it nice looking while making sure you can reach stuff hidden in the bottom of the tank if you use that gravel vac. Live or silk plants are best, avoid plastic because they can rip the frog's webbing.

I would suggest getting your frog out of that tank with the fish ASAP. ACF's are pretty persistent hunters and will eat anything that slows down enough to get in their mouth. Mine certainly tried to eat the big goldfish I had him with until I got another tank. Some people can manage it but I just can't suggest it for long term keeping. Goldfish should be avoided with ACF's because they contain a poison and their bones are hard to digest and can cause damage. They can also choke themselves on prey that's too big. Get him in that other tank without a filter, set the water level about two or three finger widths short from the top and keep it covered, if he can climb out, he will and it can very easily spell his doom.

Once you get him(or her) all set, you can look forward to a great pet far into the future (they can live ten years, twice that if they're from good stock). I really enjoy my Albino ACF, Takeo, he's the best spur of the moment pet rescue I've ever had.