Thank you so much!

Yes. But it is commonly called "Seepferdchen" as it is so small and the "-chen" is used because of that. It also reiterates that they are lovely. Like "Mädchen". A small, lovely girl.

In German, "the seahorse" is typically translated as "das Seepferdchen." "Seepferd" is also used to refer to a seahorse, but "Seepferdchen" is a more common and diminutive term. Both terms are correct, but "Seepferdchen" is often preferred when referring to seahorses.