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I bought a Cory a couple days ago and the first day he was swimming around my tank and he was quite active, but by that night he had started acting weird. He lays inside my plant, tail down, I thought he had died. I went to get him and he moved a little, so I moved my plant a few more times until he got out, then he went to the bottom of my tank and layed there. He keeps laying in my plant, though. I have another plant, but he always lays in this one, and he also just lays at the bottom of my tank. He'll eat when I feed my fish in the morning, but other than that he just sits at the bottom and doesn't swim much or goes inside my plant. Is there something wrong with him, or do a lot of Cory's act like this? Is he sick or dying?

Too early to tell, but if the fish is in distress, the best thing to do is to leave it alone, lest you hasten its demise.

Sometimes Corys just "sit around." Other times they are quite active. There is little rhyme or reason as to why and when.

Additionally, Corys do better in groups. A solitary specimen may hide in your plant because it feels threatened from a lack of fellow tank mates.

Only time will tell if your Cory is in distress or not. Keep a close eye on it. Other than that, not much you can do, until something more discernible transpires. Cheers. - Frank

Frank's advice is very good

How long has the tank been set up & have you any readings for the water - like nitrate, nitrite, ammonia, pH, temperature?

A pic of the tank (& fish) might also help.

What sort of cory is it? There is a lot of very poor quality stock out there of some of the more common species & these seldom do well for long depending on the condition they are in to begin with.

Close monitoring of the fish will be key.

Nothing is sadder than a lone Cory. Even similar Cory's would be better than none. I would have six or more if the tank is large enough. They often lay around and some are more active in the evening I have found.