What are those markings on the belly that can be seen in the last picture? Are they stripes?
If so he may be a juvenile Arothron stellatus. Look at the link I provided; though I hope I am not right as those guys get 4 feet in length. The stripes on the belly fade with age; how big is this cute puffer right now, and how long have you had him or her? http://www.fishbase.org/Photos/Thumbnai ... hp?ID=6526
-Michelle
Prevent unnecessary deaths due to disease- quarantine ALL new additions at least 4 weeks in a separate tank before adding to your main display tank!
Puffers: Hindenburg the Figure Eight, 75gallon Brackish
This puffer can reach 4 feet and is one of the more aggressive arothrons.
Really need to quarnatine puffers in a bare bottom tank for at least 6 - 8 weeks as they are notorious for having external parasites and internal worms.
The bigger the puffer gets, the faster the growth rate. Probably inches a month, especially when small. I'm not sure a tank exists that can house one of these as it gets older... perhaps find a local aquarium able to take it when it exceeds the physical limitations of home aquaria?
Maybe check with local reefers... I doubt any will have a tank large enough, but someone may have connections and be able to figure something out with you. Best of luck!
-Michelle
Prevent unnecessary deaths due to disease- quarantine ALL new additions at least 4 weeks in a separate tank before adding to your main display tank!
Puffers: Hindenburg the Figure Eight, 75gallon Brackish
Your puffer is very cute. It looks like a dogface puffer but I'm pretty sure it's not.
It is a little stressed from the environment when it turns that color brown. I would check the water parameters. The white mark you mentioned is actually some surface scrape from losing the slime coat in that area. A lot of times it'll happen near the eyes. My puffer does that occasionally when it swims too fast and hits the rock. It's not serious because puffers will do that. They love to own the tank and explore. But I don't buy rocks that have sharp edges. I feel the rocks with my hand and file down really sharp edges. The tank water needs to be well maintained and give your puffer NovAqua every time you see the scrape. It will heal really fast.
If your Petco sells RealOcean water, I really recommend this and not mix your water. Pufferfish diet requirement usually causes the ammonia to go up. And I don't have this problem with RealOcean water. Petco will order the water for you so you can pick it up. You'll actually end up save money from having good water and not buy all kinds of chemicals to correct the water. I use RealOcean water because the water is always great and I only change 10% to 15% of the water weekly.
Another thing I find is that using the live sand really keeps the PH at the desired level. Even RealOcean water cannot do that alone. Puffers love blowing on the sand because this is how they usually find food in the wild.
I also use a very powerful protein skimmer. I like Red Sea Berlin protein skimmers. The water, live sand and the protein skimmer keeps my puffer happy. Of course I have a filter system but I don't have a strong preference in this. The reason I'm saying this is because I've wasted thousands of dollars when I first got my puffer trying to make him happy. All he needed were only these things, and now I have more free time to keep him company instead of spending hours cleaning the equipments. I rotate cleaning equipments weekly so it's not a big burden.
I have my dogface puffer for over two years and he's not growing that fast. He grew over an inch possibly close to two inches. I think puffers in the standard home aquarium would not grow that big (over a feet). But having a large tank (over 100 gal) is really important.
Enjoy your puffer. It will communicate and love you back. Mine actually says hi and he knows his name. Oh, I read somewhere that puffers don't jump out of tanks. Yes, they will. So, you'll need to cover your tank. I put small towels over the gaps.