He learns it perfectly.

"Would you like to play in one of the concert wells for a few hours? We welcome anyone who is trying their best and I think you might like dance-playing."

"That sounds fun, when and where?"

"Oh, we just swim up to one and ask if we can join in. If you hurt the instrument before buying it you need to pay to fix it though."

She puts up a circular sign on her 'shop' that says 'no music teacher now, try two coves to the right' and starts swimming off.

He follows!

The concert wells are where that background music that's everywhere is coming from!

Apparently the whole underwater complex is designed to funnel live music into all the semi-public areas, with little overlap between two concert wells. The first one they try is happy to have two slelk'il players extra, but there are already at least a hundred merfolk here, playing various instruments and singing. It wells up into an effect not unlike a good-quality choral choir.

Dance-playing is apparently when everyone swims in elaborate patterns that are automatically in time with the music by virtue of the music changing when everyone turns at once. Three different layers are playing for three different patterns. Over, under, around, through. Coordinated underwater acrobatics. Nobody leads the impromptu band, exactly, but there's a clear direction none the less.

Ooh that's really pretty! He'll do that.

He should probably watch for a minute or so first, to get a feel for the patterns.

Yes, good idea, he'll do that, first. Then he'll join.

Many of the merfolk here give him interested looks, but he's being respectful and has a tail and moreover is playing well, so they make room for him in the pattern. The one that brought him here grins at him whenever the dance-playing brings her near.

He grins right back! Eeeee~

Mer come and go freely. The music is all of a similar overall style, though there do seem to be genres.

Eventually, the pattern changes, and she says, "This one uses different instruments. You do seem to like the slelk'il though!"

"I like it a lot! But I wouldn't be opposed to trying different ones."

They could do that all day.

Many of them integrate movement into the playing somehow, but not all.

He literally cannot get tired! But he does keep an eye on his guide to see when she might want to return to her stall or something.

She's having great fun. She's had to fend off several attempts to poach Sadde with the claim that she is best suited to teach him merfolk music.

She does eventually ask, "Have you decided what kind of instrument you would like?"

"I like them all! There's nothing like them back home. But I think I'll get the slelk'il and," he names one other instrument he particularly liked.

"Ah, could choose two specifically or would you like me to?"

"Hmm, your pick! Just, not the literal most expensive, I have a plane to catch later."

The slelk'il she chooses is fourteen-keyed and prominently blue with wave motif. The xylophone-like thing is sleek black, made with a combination of stone and wood. They both have low-key anti-wear magic.

4100 Kava.

Hmm... Are there similar ones without anti-wear magic?

Not really. It's featured in all but the very cheapest of them.

Oh. Well, okay, he'll take those, then.

They still haven't exchanged names, but the music teacher/shopkeep insists that she had lots of fun and it was a great day, and wishes him luck. Though she still doesn't know what a 'plane' is.

Well, airship. He tells her his name, if she ever needs him for anything, then swims back up. Very fast.