Is my tank crowded please help all fish people I want my fish to be Happy (10 POINTS BEST ANSWER!!!!!!!!!!!!!)?

I have 4 guppies, two red wag platies in a five gallon tank with live plants, heater, air-stone, filter and everything needed to take care of fish and their doing fine and flourishing they look so happy i wanted to know am i doing anything wrong and is my fish tank crowded Again they look happy and fine I also have another question i have a betta and a mystery snail in a one gallon tank he looks happy the tank has live plants gravel no heater or filter though it has a light. they look happy too so tell me if i'm doing something wrong i just started my fish interests and just started the hobby.