I got 2 miniature puffer fish for my friend 2 weeks ago and when i got them from the pet store the young man gave me these flakes and some rocks. I assumed they were a simple fish. I also bought a little travel tank for the fish till it was her birthday. On her birthday i but a couple flakes in the mini tank and the next morning they were still there and the water was a tad cloudy. My friend added new water to the bowl and took out the flakes. Then she waited a while to crumple up the large thin flakes into manageable sizes. That was 2 weeks ago. today she called me to let me know that one of the fish had died yesterday a couple hours after she switched the fish into a new bigger tank.I don't know if one of them died b/c it didn't get used to the new tank, or because it didn't eat very much. What should she feed it or do to prevent the other puffer from dying?