@AdoraBelle Dearheart drew this thread to my attention, so I will offer some advice here. I will take it as confirmed that the 55g tank is 4-feet (120 cm) in length, it needs to be for the loaches.
Bolivian Ram males are territorial. The extent of an individual's territory can depend upon a few factors, but it is never advisable to add fish of the species once a male has settled in to a tank. He probably considers the tank "his," this is their inherent nature. If you were to add several rams, say 7 or more, likely some would be female and he might decide to pair up. Rams must select their mate from the group, they will not accept any female (or male by a female). Once a pair seems to have formed, all the other rams may need to be removed; their presence may or may not work out, depending upon the initial fish.
Another male might or might not work. The male now in the tank may have decided this is his space, or maybe not. It is however a real risk.
I acquired a beautiful male Bolivian in 2008, and he was housed in my 5-foot well planted Amazonian riverscape tank all his life. About two or three years after I acquired him, I found a group of rams in a local store that were in very good condition, so I thought I'd get him a mate. This was obviously before I understood the species. They seemed to accept each other, though in hindsight now I can see there were very clear signs that this would not last--and it didn't. They spawned four times, then the male decided he'd had enough and he killed the female overnight. Even in that long a tank there was no escape.
This species has a 4-5 year lifespan. My male lived into his ninth year. During his life, it was obvious that the entire tank was his space, and every other fish knew it. Rams are substrate feeders, so he ate the sinking shrimp pellets, tabs, etc that the cories ate, and there were 60 cories in this tank, mixed species. He would poke any away from "his" pellet or tab, but nothing worse ever ensued. I noticed that he had much less acceptance/tolerance for cory species that were not spotted; the spotted ones, like C. schwartzi, C. leucomolas, etc were always ignored, but the C. duplicareus, C. panda, etc were always poked away from his space when eating.
One day I noticed the group of nine Bleeding Heart Tetras were hovering in the upper third of the tank, midtank. I wondered why--then I saw why. The Ram was below them, and whenever one of the BH began to move outside this tight group, the ram charged toward it, and back it would go. There was never any physical contact, but the Ram was clearly exerting his "right" to the tank, and the BH had obviously riled him over something. Fish use chemical communication as well as visible, and the Ram was likely releasing allomones that the BH could read, exerting his authority.