ok, slooow down for a moment. Firstly, a 55g is too small for a Mala long term BUT, assuming we're talking about a baby (sub 8") a 55 will be ok for the short term. Malabaricus are not fussy eaters and never will be. They are, however, opportunistic. Ignore the suggestions of transferring them onto different species of live for the moment and focus on dead foods. When i was breaking my Tatauaia off of live, the thing i noticed was their fixation with eyes and the closer dead food resembles live, the easier it was to break the dependence of live food. Now, going out on a limb here because i am not in the US, my guess is that the fish available as dead food will be lance fish or similar. Assuming these are whole fish, try throwing one or two in the tank in the evening and see what is left in the morning. If it's not taken, remove the waste as it will spoil and repeat in the evening. Bear in mind, they are more intelligent that some fish that will starve. It wil not starve itself to death and will seek alternative food so be sure that if it has tank mates, they are not snack size. As long as the food you place is fresh, eventually he will take it but it may lead to some amount of food being thrown away until he eats it.
In regards to your ammonia level, I'm afraid this is something i have never had an issue with so i can only echo what others have said time and time again. If you are over feeding or leaving too much waste in the bottom to tempt your wolf to feed, you will be causing spikes so make sure that the morning after a feed, you clean any waste immediately so that the bacteria in your filter have the chance to clear the overload.
Above all, if you're worried about the water, keep the water changes up. 20-30% daily for a week or more is better than a 50% weekly and infinitely better than a 90% change. It gives your filter time to establish and avoids causing too much shock to your wolf.
Good luck.