Nicole, I dont claim to be an expert or anything, but i’ll tell you what i know. Now, the general rule is about 1 inch of fish length per gallon. you can house 45+ in that one.
now, when you say you just bought one, did u like just buy it a day ago and put fish in already? if you did, dont be surprised if some die. you need to take things slow and let things kind of “age”, if you will. for example, im replacing my old pump, so i bought a new one, put it in and letting it run for a month in there with the old one still working. it will age and get some bacteria in it and such and only after than i can pull the old one, because if i just switch, it will offset the chemical and biological balance in the tank and can easily kill the inhabitants.
its easier with a 55 because of the sheer volume. that gives you a larger error margin. i have a 5 gallon tank, so i watch it all the time. i sit next to it and watch my fish for a while, to see how their behavior is. if something looks or seems off i take the water to be tested. in my tank if my pH slips, i dont have that much time to wait, but with yours, you have some more room, but dont let that put you at ease too much.
I would like to get myself a larger 50+ tank as my display tank. my general plan is to get a big tank, get it well vegetated and put in mainly neon fish for lots of movement and color in it. theres obviously going to be an algae cleaning team in there(snils, cats, shrimp and the like), but it mainly will be the “look at that” and “ooooh thats pretty” tank. im also planning to get a decent size colony or two of shrimp in there. i tend to like crustaceans more than fish.
whats your general plan for your tank? do you want mainly plants or fish in there? make sure you do some reading about the fish you have, because sometimes people will get a nifty looking fish and come home to an empty tank with that one really fat fish floating around, gloating. check into the chemistry the fish need as well, some fish can live in fresh water, but its slowly killing them, because theyre brakish water fish, so make sure not to mix those guys. you can also do a balanced tank where you get a buncha bottom feeding fish like cats and plecos and such and something like a bunch of neons that school together and fill in the middle and top layers of the tank. theres really a LOT of possibilities.
Also, post pics of your setup. Somebody remind me on AIM today to take a few pics of mine. Cuz ill forget by the time i get home.