My two little puffers do that... although what is sooooo funny to watch is when my youngest son takes a toy or something and stands in front of the tank moving the item around right in front of the glass. The puffer fish will follow him for hours. Not long after to puffer start following him the barbs, swordtails, mollies, white clouds and zebras join in.
Venus aka ltldrgn13
72 gallon bow-front:
2 Red-tail Sharks
1 Rainbow Shark
3 Zebra Danios
3 SwordTails
2 Dalmation Mollies
4 White Clouds
3 Green Barbs
3 Tigar Barbs
3 Gold Barbs
3 Albino Barbs
2 freshwater Drawf Puffer fish
1 pleco
29 gallon:
Nothing but rocks & water
2.5 gallon:
1 Betta
1 gold snail