One on right definately looks male. It is extremely hard to tell on these guys because they both have odontal and pectoral growth. The rounded body, and larger head helps but I have had a hard time telling mine apart until they laid eggs. At full size males are larger but not by much atleast from my experience. Good luck
I feed veggie wafers, meat and spirulina wafers and also shrimp pellets alternating each day and then 2-3 times a week frozen bloodworms, brine shrimp or live whiteworms. Everyone has mixed reviews of what they eat mine dont really like zucchini or cucumber but I know several others they devour them. Try it and see what works best for you.