i would definitely go for an axylotl (mexican walking fish) they are quite easy to look after. if you want to see some pictures of mine, go to my website by clicking on the link in my siggy. They are actually the larval form of salamanders, but for some reason they do not turn into them ever unless a special hormone is added to the tank water. this is good though, cause then you dont have to worry about having water and land tanks. the need cold water which is simple as well. they can live to about 10 years, and they can grow back body parts. even internal organs like their heart!!! they can grow up to 30cm long, but how big they get depends on how big your tank is.

Hope i helped.