yeah looks like he either got spooked and tore it, caught it one one of the decorations in the tank or its the tetras, i still suggest getting a couple more of those guys to form a decent school, the GT is probably messing with them thats why they hide, if you get enough for them to properly school then they will have more confidence to come out during the day and wont nip the GTs fins either GOOD LUCK sounds like you have a cool set up there