carbon fiber reinforced plastic

Inside the animal? As in an implant?
You would only use carbon fiber reinforcement for certain high-stress applications. Presumably, an implant would not be subject to high stress, unless it was something like a tooth replacement or a bone joint replacement.
The question of the reinforcement is separate from the selection of the polymer. Silicones are widely used for implants.

Hi,
Yes, as an implant. My task is to protect the device completely from water or blood for a long period like months or years like protecting the crew people of submarine from sea water. Does lack of stress make this material improper to use in the RAT?
Some people do adviced me that silicone and other traditional material used in the implanatable field do not last long like for months or years. I am more concern with the leaking of the water into the electronic device. Does this material provide excellect protection against water or blood. Does it corrode with time? Please advice and be patient with me.
John

No, but there's no reason to use it either. Carbon fiber is a reinforcing filler, not the polymer matrix. You could add carbon fiber to just about any polymer, but it would only make sense when the resulting material is subject to high stress. A properly designed silicone material will last for years. It is very inert, and will not degrade. That is why it is used for implants.
Silicone does not have high strength, but if it's not being stretched, crushed, or abraded, that might not matter. There are other reinforcing fillers which can be used to increase the strength of a silicone material. Silica is most commonly used.
You could consult a patent database for examples of encapsulants used for implants.
Here's the search page for U.S. patents:
Try searching for:
spec/"biocompatible polymer"
That will get 1482 hits.

If you believe that submarine use of materials is an excellent qualification, then read below......
Seawolf is the first American attack submarine to use a hull made entirely of high-pressure HY-100 steel -- previous sumarines used HY80 steel. HY-100 steel was first used in submarines in the early 1960s in the Navy's deep-diving SEA CLIFF and TURTLE,, which were capable of reaching depths in excess of 10,000 feet. More recently, the Moray, an advanced conventional submarine designed by the Dutch shipyard R.D.M. (Rotterdamsche Droogdok Maatschappij B.V), incorporated HY-100 steel to achieve an operational diving depth of 300 meters, and an incidental diving depth of 360 meters.
Submarine hull materials are selected to withstand seawater and great pressures. This doesn't have much to do with your application.
Just research what everybody else is doing to encapsulate electronic devices for implantation, and pick one of those that meets your needs...whatever they are.
There is a long track record of biological encapsulation of electronic devices .... and metals or polymers have been selected for various reasons.
Just look at what others have done that is remotely like your application, and consider those as your primary "pick list". Then your budget or ability to work with the different materials or vendors will narrow it down some more.
Medical grade silicones are probably reasonably cheap, easy to get, you can get lots of help from manufacturers.... and there may be some of the stuff lying around your establishment already.
There are other medical grade polymers, but what is special about your application that may need one material rather than another>