I had 5 in a 140 litre tank which didnt turn out so good, they also struggled to compete against my other very common fish (danio, keyholes and BN). I found that one of them ate alot and the other did not, they loved live worms and algae wafers and yet one day they all stopped eating, I could not figure out why. Eventually they died which was pretty demoralizing being my first fish (I presumed they were relatively hardy)
If you go by the facts you need more than 5 as they are very social fish otherwise they may be too "boisterous" (mine weren't) Offer them alot of little caves, and hiding places (they get stuck when worried) they also play dead which can be very confusing. There is an excellent website called the Loach Almanic (I think?) which is dedicated to loaches. I think with your tank the dwarf chain loach would be better suited or the polka dot loach (if you can find any) as they are a smaller type.
If i was to keep them again I would use a sand substrate, subdued lighting and probably a species only tank.