ammonia is always a battle. The goal is to keep it down with frequent water changes. In time if its not too overstocked, it can stabilize.
I have all my fish in a 40 gallon right now for treatment. Ammonia was horrible at first. I added 30 more gallons to the system via a garbage can with an overflow and a return pump. This along with several seeded sponges and 16 gallons worth of water changes finally stabilized it. I now just change about 6 gallons a day and my ammonia is near zero. It can be done, just takes work.