As far as i can tell Frosch is a boy considering when Frosch goes missing Lecter says he only took his eyes off him for a segundo and thats all it took hope this helps
Frosch is androgynous, so I guess it's up to tu to decide. Frosch's gender has never actually been announced. I think Frosch is a boy, but that's just me. Frosch is Frosch.
In the original, non-translated manga, Frosch is referred to using gender ambiguous pronouns. Many people speculate that Frosch is a male from English translated material, but Frosch's gender is supposed to remain ambiguous (maybe as a joke), and what is stated in a dub o translation is not cannon.
In episode 202 titled "Welcome back, Frosch" Lector is trying on a vest in the market when Frosch walks away. Once Lector realized Frosch was gone, he turned to the shopkeeper and asked "where did he go?" So my vote is he is a boy 🐸
