My 30 year old sister's friend recently bought her a retro Barbie (no, it's not a typo, my THIRTY year old sister has a Barbie doll!) and she fell in love with the knitted and crochet dresses I made for my daughter's doll. Her favourite Disney cartoon growing up was 'The Little Mermaid' so when I found some Freedom Gorgeous yarn at half price for £1.79 per 50g ball in my local Hobbycraft (I needed just over one ball), I decided to make an uber-bling version of my doll's demure mermaid dress for her complete with gold edging using Twilley's goldfingering on the scales.
I made a few modifications to improve the pattern. In the original prototype, I made the scale section and continued up through the bodice. I then made two tail fins that I stitched into place. The new improvement is that I made two half tail fins, joined them by crocheting them together, then decreased gradually to 8 stitches into which the first eight skeleton pairs were worked. Please scroll right down to the bottom of my post on working double crochet in continuous rounds and refer to crochet stitch summary and terminology.
I have worked hard creating my original patterns and am happy for
them to be used for free. Please do not sell the patterns. If you do
sell the end products please state clearly that they were made using my
design, and that the pattern came from
www.craftymamasanchez.blogspot.com. Thanks, and enjoy!
Made using continuous rounds. Do not turn work.
Round 1: Ch 2, 6 dc into 2nd chain on hook
Round 2: 2 dc into each stitch round 
Rounds 3-5: Work without shaping for 3 rounds
Round 6: (1 dc, inc1) x 6 
Rounds 7-9: Work without shaping for 3 rounds
Round 10: (2 dc, inc1) x 6 
Rounds 11-17: Work without shaping for 7 rounds
Join the tail fins in round 18 by working 24 stitches on the the first tail fin then 24 stitches from the second tail fin 
Round 19: (4 dc, invDec) x 8 
Round 20: Work straight without shaping 
Round 21: (3 dc, invDec) x 8 
Round 22: Work straight without shaping 
Round 23: (2 dc, invDec) x 8 
Round 24: Work straight without shaping 
Round 25: (1 dc, invDec) x 8 
Round 26: Work straight without shaping 
Round 27: Dc2tog x 8 
Do not break yarn, instead continue straight into the tail by working the first 'skeleton round' as follows:
Slst to next stitch, 3 ch, tc into slst, ch 1, (2 tr, 1 ch) into each of the 7 remaining stitches round [8 skeletons formed.
Resume working from the doll's demure mermaid dress pattern. If you would like to add a contrast trim as I did, join in the contrast colour after fleshing out the scales and work a round of dc. Do not break either yarn - the yarn will not need to be trailed for long distances. Work the second leg of tc on the first scale of each round such that you wrap the contrast yarn.