The beard makes me think it's based on a monkfish, which would be a fish known to most Japanese people?I like how the notes on Gerai are appropriately inaccurate.
Like the inspiration for Gerai was clearly anglerfish and frogfish, but Kariyasu Tokuda is probably not someone who would have ever seen those guys, so she's just like, "yeah it's sorta like a frog and a fish???"