mine is the same. they are sensitive. make sure you have the lid closed completely. they are jumpy. mine doesn't get that much since you saw him in the 10 gal he is in the far corner of the room and no one gets their too often only me. and now i have him in the back divider to make him less skitish on his environment.
i would suggest you get some black paper and try to cover the sides. they get shock a lot. and avoid sticking your face in there tank. they would think a big fish is going to gulp them! joking aside... cover the sides and back and make him feel comfortable. no need to put hidding place. it may help but he might end up injuring himself or maybe not.
man its got a busted upper lip and thers something going on with the gills. is it possible that the gills can be damaged at this size? it seems like the one sideof the gill is a lil bent. or maybe it isnt ....