You can't keep either of those fish in a 27, hippos hit 10 inches and nasos get much larger. Suitable fish for a nano tank are smaller clownfish, blennies, gobies, etc. but you need to research how large and active fish are before you get them.
Debra - please tell me that you dont have any Tang in your Nano tank? These fish get VERY large and need room to swim. I have both in a 180 and they will need more than that in a year or so.
Your 27 gallon tank will kill these fish due to the fact that they need swimming room.
Please return the fish to the LFS where you bought them so that they can be placed in a proper aquarium for a good and healthy life.
Originally Posted by DebraPurdy
i will when he gets alittle bigger he is very small
You got a UV hooked up right? Is the hippo disease free? I wouldn't want to risk putting such a disease likely fish in a tank that I won't keep it in.