Your fish is floating on the surface because it is dead.
floating like fish
fish in tanks are magnified by the glass and the water.......... in my round fish bowl my guppies look huge
Fish do not normally "float around" they swim. If your fish is floating/sinking then it is probably dead.
Because most fish have really good senses when you touch the glass. They have keen sense of seeing things. Some fish do, but they are mainly SENSITIVE
It is caused by the magnifying effect of the glass/plastic and water.
This happens when the fish is dead or dying.
That may be that your fish is dead.