I 100% agree with the method Bderick67 posted, you MUST get the ammonia below 0.25-0.3, change as much water as you have to. High ammonia (above 0.5), or prolonged exposure to lower levels causes permanent damage to fish's girls, which are their lungs, liver, and kidneys.
Seed your filter, some of the bio media (20% of what's in the 55 wouldn't hurt.) Adding the "crud" from the filter might help, but generally that's just waste that hasn't broken down fully, and will just add more ammonia to the tank as it decomposes.
Also that water conditioner is a good mention, when you add water directly to the tank without dechloring it prior you have to add conditioner based on the tank volume, not what you're adding. Get Prime, Amquel Plus is also good, ends up costing more as it's not as condensed.
Agitate the surface as much as possible, move the spraybar above the surface, blowing length wise. The extra oxygen added to the water will help the bacteria, as well as outgas some (not much) of the Ammonia.
But do as Bderick67 said, and please change as much water daily as it takes to keep the Ammonia (NH3) below .3. The cycle will take longer but your fish won't die an early death or suffer long term health problems.
Most of the advice has been good, time and lots of water changes is the only safe way to sort this out. Good luck!
Oh, once the ammonia drops your nitr
Ites (NO2) will spike, you'll need to do frequent water changes then also, as well as adding aquarium salt to reduce nitrite toxicity (which causes brown blood, often fatal.) Once NH3 and NO2 are 0, and nitrates are showing it's time to slowly get into a routine of two 20-40% bi-weekly or one 50% weekly water changes.