Yeah I would he'll be fine just watch him and give him some weeds to hide in if you can. Depends on how valued the fish you're protecting are to you. It's a disaster if your prized fish get sick over one guppy. Better safe than sorry. I mean all these little rules are tried and true and tho at times seem redundant when something goes wrong (and it will) at least you'll kno you did all you could. Also I feed garlic before and after adding any new fish. I'll starve them for a day and mix it with frozen and whatever fruits/vegetables I have around the house. Some fish are more delicate than others and stress triggers sickness so use common sense. I don't know what you're keeping but I have a lot of "scale-less" fish that are susceptible to poor water quality, disease, etc so it's important to handle with care. Also if you're keeping wild caught might not want to just buy them anywhere. I bought my SAP from the best store in the state where I know he quarantines his imports before they go out on the floor and even got them to start accepting freeze dried krill. Now I paid a premium for his service but I haven't had any issues... just sayin