Considering only the information provided, here goes.....
If the water temperature and the air temperature are pretty much the same, that's not a good thing. Thermoregulation is a very important part of your animals natural behavior. If the temperature is all the same, he will not be able to properly thermoregulate.
I generally have water temps no lower than 76 and no higher than 79-80. Generally, 78 degrees or so would be perfect IMO. Air temperature needs to be approximately low to mid 80's with a basking spot to help boost his temperature to their preferred body temperature (PBT) of 88 degrees. A basking temperature of about 105 should be sufficient. Typically, when I setup a basking site for my crocs, I setup the lamp so that there is a main beam which will be directly heat of about 110 degrees, however, there is enough space on dry land that they are able to move away from the beam as they see fit therefore, lowering basking temps from 110 to 100 to 95, etc, etc. This will allow for proper thermoregulation and in the end will make your animal much healther.
That's just for starters. Variety is the key to a healthy crocodilian. You also want to make sure that you are using a good vitamin supplement. Miner-all is a good supplement and I am sure there are others out there as well. Chris Dieter states that he has had luck simply using a human adult multivitamin. If you choose to go this route, then you want to be certain that you aren't going overboard on the amount given if he is only 7 inches long. I would only provide maybe about a quarter of the full sized pill.
I could go all evening, but it appears you have some research cut out for yourself. To help you out, here are a few sources of information.
www.crocodilian.com/crocfaq (Dr. Adam Britton's website)
www.crocodopolis.net (Israel Dupont's website which has alot of different links to provide you with research materials)
www.thecrocodileexperience.com (Chris Dieter's website, yet another excellent source)
www.herpfanatic.com (My personal website, just click on the "crocodilians" link and have at it.)
Hope this helps, and good luck.
Chris
-----
My Website
www.herpfanatic.com