Useful daily expressions: buying fish

One month ago Kitaoka-san planted two lotus roots in a pot of soil and water at our front door. A few days later, Mari and I left town for about three weeks, leaving the task of watering to our helpful neighbor. We came back home to find healthy bright green pads growing from a dark soup redolent with the earthy-sewer smell of life. We also found tiny red wormy things squirming in the water —  mosquito larvae, something Kitaoka-san had warned us about. Our little ecosystem needed balance.

Today's mission: go to the pet store and buy medaka, small fish which would eat the mosquito larvae. We decided the errand would also be a good opportunity for me to practice my rudimentary Japanese. Over dinner last night, Shigeo-san dictated a script for me (language students take note):

めだかを　よんひき　ください。medaka o yonhiki kudasai.
にひきは　めす。nihiki wa mesu.
にひきは　おす。nihiki wa osu.
Four medaka please.
Two male.
Two female.

I'm reporting back on my blog, as assigned. きょうは　くろめだかを　ごひき　かった。Today I bought five black medaka. (Five was the minimum order.)

The shopkeeper expertly netted five medaka — how do you tell the males from females? — and tied them in a plastic bag for me. I hung them from my wrist as I pedaled my bike home, and I slipped them into the water. Each is a bit over 1" long, and more grey than black. They seem to be enjoying themselves, darting around the water and swimming up to the edge of the pot to find food. A worrisome note, though: three separate times, I had to rescue fish that jumped out of the water into the flowerbed. The first time, I only noticed by chance the tiny escapee wiggling in the dirt. The second escape was almost as easy to miss. After checking on them a few times, I decided not to worry too much about it. If they're going to jump out, what can you do? So I won't be surprised tomorrow if there are fewer than five left.

Update:
Not more than 6 hours after I brought the fish home, they're all gone. I think a bird ate them? Or they buried themselves? There is not much room to hide in that pot, and I don't see anything moving nor any dead fish bodies. Also, I just remembered that mizcat wrote about a similar experience a couple months back.