[i have crabs]

ich is a parisite that has to be killed off or starved to death,so if you have fish in the tank they will or do have ich weather you see it or not,the garlic and cleaner shrimp is some of the worst advice ive ever heard and its the first thing i see posted every time,garlic and cleaners cannot and will not cure ich. at best it will boost the imune system enough for them to fight off a full blown out break and you fish will look healthy but they wont be.
the best thing you can do is go buy a 20g and a cheep heater and a aquaclear 50 wich will cost you about 60-70 bucks new and a lot cheeper used get some coppermine and a copper test kit for another 25 bucks and deal with the ich right now before you kill the rest of the fish you already have, hypo is another way but its alot more complicated and more expensive and does not work better in my opinion and i have done both ways more than once.
if you need advice on how to quickly cycle a new tank and do the copper thing let us know.