Hi Nospherith,
The South American Puffers teeth grow all the time unless they are worn down by diet. In the wild it crushes snails etc. and that keeps the teeth worn down. However, a combination of the South American Puffer having amongst the quickest growing teeth and mine being picky and choosy over when it will eat snails and when it won't results in the overgrown teeth.
The problem comes when the teeth get too overgrown and the puffer is no longer able to eat and starves to death. So unfortunately in this case it was essential, I left it as long as I could and Goldie was only able to take bloodworn by sucking it in the side of his mouth. So at that point I bit the bullet and clipped his teeth. He sulked for about a day, but is now able to eat properly again. In the meantime I will continue my quest to persude him to eat more snails <grins>.
As an aside, even though South American Puffers tend to be amongst the most peaceful, if they chose to they could shred probably almost any fish in my tank. So far mine has shown no signs of aggression. Other types of puffer are far more aggressive, even those cute little Dwarf Puffers <sighs>.
All the best,
Triskele.