I think they get between three and four feet. They're not large but certainly would make a good "centerpiece" for any mid-sized aquarium. As for putting it with larger fish, I donno. Assuming the fish would leave it alone, I don't think it'd try to go after anything that big so it might work. Maybe a bit of trial and error would be required. Regardless of how aquatic they appear though, it will always be important to have a spot to allow them to get out of the water if they so choose.