im not really sure, maybe. you're doing everything right, but i think you would get better feedback if you posted your issue in the freshwater diseases section
i highly doubt that as the gar looks healthy from the full-body shots of the fish.
i would agree with earlier posts that the fish likely got spooked and rammed into the glass, damaging its snout. just keep the temp up, add 1 tbsp of salt per 20g of water and bump up water changes to 50% every other day or every two days until you notice clear signs of healing. i would keep treatment up for about 2 weeks and then post updates so we can see how the fish is progressing. good luck--
--solomon