I totally "pet" my fish. In fact one of my dwarf gouramis and my common pleco will truly let me pet them. The gourami will eat out of my hand and let me touch him with the other. I just discovered that I could touch the pleco. I reached in the tank to push a plant back down but the pleco was laying too close. I touched it's tail to get it to move, but it didn't so I started rubbing it. I made it two full body rubs before it swam away... Weird I know!
I have a new funny Cory story. I have one banded Cory because the LFS
only had that one left and I figured it would bond with the others regardless of coloring. It did, but I also have two skunk loaches that are marked and colored the same way. The banded Cory is always trying to get those loaches to play. They of course want NOTHING to do with this foolish Cory Cat behavior. They go under a rock their skinny bodies can fit under but not the chunkier body of the cory. He goes back to the group of Corys and seems to say to them "but they look like me! I just thought they might like to join the fun.