Help, my Guppy is going to die.

I recently got a new male guppy (with some Zebra Danio and another male Guppy), but he is just sitting in the corner with his body perpendicular (head up, tail down). My heater is only managing a 73, so I am going right now to get a better one, but I think something else is wrong. Is there anything else I can do? Everyone else in the tank is fine and eating, but he won't move.

How long ago did you add him to the tank? It could possibly be shock.

73 degrees is fine, I wouldn't rush out to get a new heater.

pictures and short video of the fish?

what is the ammonia, nitrite, nitrate and pH of the aquarium water?

Can we have a water parameters?

My water tested normal for everything, I don't know exacts because I have the paper testers (my pH is about 7.2). I just added him a couple of days ago, so stress seems right, but now his fin is turning white? My other guppy is doing fine.