Some mythical beasts make sense to us, even if they don’t actually, logically or physically work. Many of these beasts are well liked, even thought of as pretty, majestic or cool. Most people would agree that a Pegasus is a fun beast.
“What’s better than a horse?” they say. “How about a horse with wings?” Everyone cheers.
But then there’s those less-well known beasts that are just less fun, less aesthetically pleasing…
“What about a horse that’s also a fish?” a lone voice calls out from the back. The room goes very quiet.
Hippocampus

This is another Fantastic Beast that already shows up in Dungeons & Dragons (distinguishable by the fact that D&D drops the ‘ups’ off the name) and these stat blocks are massively different. But I’m making them all, because I said I would.
The one thing I did take out is the Charge ability. Lots of D&D beasts have this: run at an enemy and then attack, do more damage. Just because your front half looks like a horse, does not mean that you can gallop under water. If the hippocamp gets an extra bit of damage for ramming into its prey, then we need to start doing that for the sharks in D&D too.
Besides, a horse might be fast and majestic on the open plains, but in water the hoof is a sub-par swimming aid at best.
Thank You For Reading
Here is where the rest of my Potterverse/D&D stat blocks can be found!