Your very lucky that the fish didnt get stuck. Those nems are super sticky and have a potent sting. I have seen many of fish get eaten by carpets that way. +1 on the quarantine. Basically its just a smaller aquarium, I would probably use a 20L, with a hangon filter and an airstone at the minimum. Just a place to hold the fish so you can keep it eating and treat it with meds without having to treat the whole tank.