Inactive Betta

Hello! I'm very new to this site and I have tried other fish forums all of which I have encountered rude unhelpful responses. 
 
Right now I have two tanks, the first is a 29 gallon which houses 15 healthy happy Tetras, the second I purchased a week ago. My friend had a male betta that she kept in 1 gallon for 6 months, she thought that since I had fish I could just take him. I did take him on however I didn't want to risk it with my tetras (I have three Diamonds that would love to nip his fins) and I wasn't going to keep him in one gallon with no filtration or heater so I went out a week ago and bought a fifteen gallon an aquaclear filter (I have one in my 29 and it works really well) and a heater. 
 
I borrowed some of my live plants from my 29 and got three large rocks which are set up into a stable, cave-like structure for him. Tonight I floated my new betta Theon in a bag and released him, I made sure all parameters were correct (I've used seachem prime in my other tank for years and it works great to detoxify ammonia, nitrite and nitrate) the pH was 6.8-7.2 and his temperature is at 77.
 
I expected him to be happy to be in so much space but he stays near the top and hardly moves. Theon also seems to be a little weak, he'll tumble a bit under the light waterfall the filter makes. 
 
His color is also very dull and when my friend first bought him he was a beautiful blue, will his color come back with time?
 

I really hope you get an answer, I'm also new and my betta is very inactive. I know they do like to rest near the top due to them having to breathe O2, and I got a silk leaf and placed near the top and my betta does lay on it quite a bit. But hardly ever swims around and waits for the other fish to eat and gathers scraps from the bottom

well he looks fat, which is never good, cut on your feeding.
you'll need to cycle the tank, if you don't you'll have the possibility of creating more issues.
he is most likely no active because he is not comfortable with the environment he is in.
 
floating the bag and then releasing the fish IMO is bad and they should be dripped in. it takes more time, but does work better to help the fish establish with the different levels of the water.
 
i would recommend that you add more hiding spots, more coverage and more plants over all. 
look at the overall of the body from all angles, are there anything that seems not normal, if so let us know and we'll help you out

Yeah, I know she did overfeed him and especially in one gallon he had nowhere to swim it off. 
 
Overall his fins seem fine and the only thing I noticed his is chest is very white and patchy in color, he doesn't even seem to bother with the large rock structure I have in there or any of my live plants but I was looking into the little floating plants, I read bettas love them and I can buy another structure. 

That was nice of you to take the betta in and give it a better life.    
 
Firstly I would bump the heat up to around 80F.  Most cases of lethargy can be fixed with a bump in temperature.  I would also fast him for a couple of days since he is so chunky from being overfed by his previous owner.  
 
The betta is probably in shock from the lack of true acclimation to the new tank at the moment.  Just floating the bag get the fish to the correct temperature but doesn't help the fish get used to the difference in water from its original environment and the new one you are adding him to.  The filter flow might be a bit strong for him if it is blowing him about.  Bettas prefer calm water and some can have difficulty swimming with a strong filter flow.  There are many ways to baffle the filter to slow the flow down a bit for him.  If the filter is not cycled, you need to be doing water changes frequently (every two days of about 50%) to keep the ammonia/nitrIte safe for the fish.  Since you have a cycled bigger tank, it would just be easiest to take a small bit of the filter media from the bigger tank's filter and add it to the betta tank's filter to seed that tank making it cycle faster.  While Prime does help with detoxifying the bad stuff it does not do so all the time which is why the water changes are so important.  While bettas do love larger spaces it is good to remember that he will probably be a bit stressed for a little while in the new surroundings since #1 it is new and #2 it is a larger territory for him to patrol.  It is always better to provide plenty of hiding areas so he doesn't get too stressed.  Floating plants are a favorite of bettas so adding them is a good thing.  I love floaters and one of my favorite is salvinia. 

Thanks so much, I was sure to get a filter with a sight waterfall and the tank is full so there's hardly a current. I also have a product called cycle, I've used it in my big tank but was weary to use it in the 15 until I got another opinion. The heat is up to 79 and he seems happier. It's the second day in the tank and he seems to be doing better, I just bought a large wood decoration that's hollow and has several holes and I was happy to see him swimming through it. 
 
I got a goodish picture of him in his new decoration. 

 
Most of the picture is window glare xD but he's in the lower right corner of the hole, his dark colors make him hard to see.

Also would someone mind telling me what type of Betta he is, I have a sinking suspicion he was not listed correctly at the lfs as a Dragon Betta...and will his color make an eventual come back? 

Bettaladda said:

Thanks so much, I was sure to get a filter with a sight waterfall and the tank is full so there's hardly a current. I also have a product called cycle, I've used it in my big tank but was weary to use it in the 15 until I got another opinion. The heat is up to 79 and he seems happier. It's the second day in the tank and he seems to be doing better, I just bought a large wood decoration that's hollow and has several holes and I was happy to see him swimming through it. 
 
I got a goodish picture of him in his new decoration. 
...
 
Most of the picture is window glare xD but he's in the lower right corner of the hole, his dark colors make him hard to see.

Click to expand...

+1 what WildBetta said.
 
The products that claim to cycle your tank do not I am afraid, if only it was that simple.  You need to take some mature media from your existing tank ASAP and add it into the new filter, so that the bacteria can start to break down the ammonia etc.  Read this Cycling Your Tank to understand more.
 
Can you tell us what your friend used to feed the Betta and what you are now feeding him?  Bettas need care in feeding, and if you have not already read the Betta Care Sheet which again would give you a greater understanding of these wonderful fish.
 
Do you have a full tank shot you can upload for us?
 
Indian Almond Leaves are also good to add to his tank.
 
His colour should come back and you are already seeing a change.  I think he is possibly a Rosetail Betta.
 
Once again welcome and well done on asking the questions and providing a good home for the fella.

When my camera battery charges I will be sure to upload a good photo. But for now I can tell you she fed him tropical flakes. I bought some Omega One Betta Pellets and I have some tetra brand bloodworms for my big tank and I read that bettas love them so I was thinking of giving him one or two of them everyday. However, now as per Wildbettas instructions he's not eating but I'm pleased to see him 'dance' along the front of the tank when I walk by. I haven't seen the live plants I'm looking for in the LFS is there any aquatic place online to buy good live plants? We used to have a great HUGE fish specialty store but I guess it was too expensive to keep up so they went out of business and all we have now is Petco and Petsmart unfortunately. 

A few blood worms a day would be too much, a bit too fatty for him.  I give mine a couple once per week.
 
The betta pellets would be the ideal and perfectly balanced diet for him.  I feed mine 5-8 pellets (pre-soaked) per day.
 
I like Aqua Essentials for my plants.

If the bloodworms are freeze-dried it's best to soak them before you feed them to him. Freeze-dried blood worms can cause digestion problems. 
 
That he is starting to dance for you is a good sign!