I bought a dwarf puffer fish last Saturday, put it into my 6-gallon tank, With a PH of 7, 0 Ammo.
It is heavy planted(java moss tree, Staurogyne Repens, and Hydrocotyle tripartite)
The tank had been cycled for 3 months with an external canister filter for 10-gallon tank.
A regular 10% water change every 1 week
Also, there are hundreds of pest snail in the tank, but they are tiny.
The fish looks healthy but it won't eat. I began to suspect it has the internal parasite.
Here are some symptoms I can observe:
1. it keeps curling its tail(I know it can be a sign whether it is happy or stress)
2. I can see white fuzzy thing on my moss(but I'm not really sure it is algae or white stringy poop)
Here are the symptoms I haven't observed:
1. Sunken belly
2. Skinny body shape
Here is how I fed it:
I only tried frozen bloodworm and snail for past 3 days:
1. I tried to tie the bloodworm on a fish wire, or to use a baster, and then swing in front of it. It appeared to be attracted by moving items, it touched the food and left.
2. I tried to throw snail in front of it. Nothing happened.
3. I crack a snail in front of it. Nothing happened.
This is how it looks like

And this is how I fed it:
