It has been laying upside down in the bottom for 3 days and yesterday it made dark blue/green poo 0.o. I will try to give it a pea for constipation.
I know absolutely nothing about this type of fish, but for swimbladder problems that may be cured by dealing with constipation, the best method is using 1/8 teaspoon of Epsom salt with 4oz of food & use that to feed your fish for a few days. Epsom salt is a natural laxative for fish and usually does the trick. Of course I have no idea if a gar can have salt, so it will depend on that.