Of course it is. Soon you'll be telling me that a cow isn't a fish!
Cows are fish the same way the dolphins are! -
Krowa jest rybą tak samo jak i delfin!
Are you joking? ☺
Most of the time.
It is a mamal :-)
Delfin jest ssakiem, ale je ryby.
Mammal is 'ssak'? What's the etymology of that?
Well, it sounds kinda weird if you think about it. But it comes from "ssać" (to suck), because mammals suck their mom's milk... (can you say that in English? - well, anyway, you know what I mean).
Ok, it's a pretty similar etymology. I suppose what I was really wondering is how it ended up with a double letter at the beginning...
If you really want to know why: this word comes from Old Slavic sъsati, it ended up with a double letter due to the loss of the weak vowel ъ (it was pronounced like the "u" in "pull")
Hmm. I have no answer for that, but at least it's consistent with the verb ;)
Out of curiosity what's the fish called a dolphin in Polish (dolphinfish, mahi-mahi)
Wikipedia redirects to this entry: https://pl.wikipedia.org/wiki/Koryfena