They are bottom-up seamless bottle socks with stranded colourwork. 
This will be a fun project that utilizes a small ball of yarn. 
The length can be adjusted depending on the height of your bottle. 
You can also attach a string with an I-cord. 
There are colourwork charts for Goldfish, Kissing gouramis and ribbon as a bonus.
KNITTING NEEDLES 
3.25 mm (US3) a set of 5 double pointed needles
YARN 
Fingering or Sport weighted, any scrap yarn in your stash
NOTIONS 
1 marker, 1 tapestry needle, 4 beads or mini buttons